diff --git a/modules/rostests/apitests/shlwapi/AssocQueryString.c b/modules/rostests/apitests/shlwapi/AssocQueryString.c
new file mode 100644
index 00000000000..ccf6ec1c91b
--- /dev/null
+++ b/modules/rostests/apitests/shlwapi/AssocQueryString.c
@@ -0,0 +1,187 @@
+/*
+ * PROJECT:     ReactOS api tests
+ * LICENSE:     LGPL-2.0-or-later (https://spdx.org/licenses/LGPL-2.0-or-later)
+ * PURPOSE:     Test for AssocQueryStringA/W
+ * COPYRIGHT:   Copyright 2024 Katayama Hirofumi MZ (katayama.hirofumi.mz@gmail.com)
+ */
+
+#include <apitest.h>
+#include <shlwapi.h>
+#include <stdio.h>
+#include <versionhelpers.h>
+
+typedef HRESULT (WINAPI *FN_AssocQueryStringA)(
+    ASSOCF cfFlags,
+    ASSOCSTR str,
+    LPCSTR pszAssoc,
+    LPCSTR pszExtra,
+    LPSTR pszOut,
+    DWORD *pcchOut);
+typedef HRESULT (WINAPI *FN_AssocQueryStringW)(
+    ASSOCF cfFlags,
+    ASSOCSTR str,
+    LPCWSTR pszAssoc,
+    LPCWSTR pszExtra,
+    LPWSTR pszOut,
+    DWORD *pcchOut);
+
+static HINSTANCE s_hSHLWAPI = NULL;
+static FN_AssocQueryStringA s_fnAssocQueryStringA = NULL;
+static FN_AssocQueryStringW s_fnAssocQueryStringW = NULL;
+static CHAR  s_szTextFileA[MAX_PATH] =  "";
+static WCHAR s_szTextFileW[MAX_PATH] = L"";
+#define NON_EXISTENT_FILENAME_A  "C:\\ThisIsNotExistentFile.txt"
+#define NON_EXISTENT_FILENAME_W L"C:\\ThisIsNotExistentFile.txt"
+
+static void TEST_Start(void)
+{
+    ExpandEnvironmentStringsA( "%APPDATA%\\This is a test.txt", s_szTextFileA, _countof(s_szTextFileA));
+    ExpandEnvironmentStringsW(L"%APPDATA%\\This is a test.txt", s_szTextFileW, _countof(s_szTextFileW));
+    fclose(_wfopen(s_szTextFileW, L"w"));
+    trace("%s\n", wine_dbgstr_a(s_szTextFileA));
+    trace("%s\n", wine_dbgstr_w(s_szTextFileW));
+}
+
+static void TEST_End(void)
+{
+    DeleteFileW(s_szTextFileW);
+}
+
+/*
+ * "shlwapi_winetest assoc" already has many tests.
+ * We just do additional tests in here.
+ */
+
+static void TEST_AssocQueryStringA(void)
+{
+    CHAR szPath[MAX_PATH], szAnswer[MAX_PATH];
+    CHAR szDebug1[MAX_PATH], szDebug2[MAX_PATH];
+    HRESULT hr;
+    DWORD cch;
+
+    /* ".txt" */
+    lstrcpynA(szPath, ".txt", _countof(szPath));
+    cch = _countof(szPath);
+    hr = AssocQueryStringA(0, ASSOCSTR_EXECUTABLE, szPath, NULL, szPath, &cch);
+    if (IsWindowsVistaOrGreater())
+    {
+        ExpandEnvironmentStringsA("%WINDIR%\\system32\\notepad.exe", szAnswer, _countof(szAnswer));
+        ok_long(hr, S_OK);
+        ok_int(cch, lstrlenA(szAnswer) + 1);
+    }
+    else
+    {
+        lstrcpynA(szAnswer, ".txt", _countof(szAnswer));
+        ok_long(hr, HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND));
+        ok_int(cch, _countof(szPath));
+    }
+    lstrcpynA(szDebug1, wine_dbgstr_a(szPath), _countof(szDebug1));
+    lstrcpynA(szDebug2, wine_dbgstr_a(szAnswer), _countof(szDebug2));
+    ok(lstrcmpiA(szPath, szAnswer) == 0, "%s vs %s\n", szDebug1, szDebug2);
+
+    /* s_szTextFileA */
+    lstrcpynA(szPath, s_szTextFileA, _countof(szPath));
+    cch = _countof(szPath);
+    hr = AssocQueryStringA(0, ASSOCSTR_EXECUTABLE, szPath, NULL, szPath, &cch);
+    if (IsWindowsVistaOrGreater())
+    {
+        ExpandEnvironmentStringsA("%WINDIR%\\system32\\notepad.exe", szAnswer, _countof(szAnswer));
+        ok_long(hr, S_OK);
+        ok_int(cch, lstrlenA(szAnswer) + 1);
+    }
+    else
+    {
+        lstrcpynA(szAnswer, s_szTextFileA, _countof(szAnswer));
+        ok_long(hr, HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND));
+        ok_int(cch, _countof(szPath));
+    }
+    lstrcpynA(szDebug1, wine_dbgstr_a(szPath), _countof(szDebug1));
+    lstrcpynA(szDebug2, wine_dbgstr_a(szAnswer), _countof(szDebug2));
+    ok(lstrcmpiA(szPath, szAnswer) == 0, "%s vs %s\n", szDebug1, szDebug2);
+
+    /* NON_EXISTENT_FILENAME_A */
+    lstrcpynA(szPath, NON_EXISTENT_FILENAME_A, _countof(szPath));
+    cch = _countof(szPath);
+    hr = AssocQueryStringA(0, ASSOCSTR_EXECUTABLE, szPath, NULL, szPath, &cch);
+    if (IsWindowsVistaOrGreater())
+    {
+        ExpandEnvironmentStringsA("%WINDIR%\\system32\\notepad.exe", szAnswer, _countof(szAnswer));
+        ok_long(hr, S_OK);
+        ok_int(cch, lstrlenA(szAnswer) + 1);
+    }
+    else
+    {
+        lstrcpynA(szAnswer, NON_EXISTENT_FILENAME_A, _countof(szAnswer));
+        ok_long(hr, HRESULT_FROM_WIN32(ERROR_FILE_NOT_FOUND));
+        ok_int(cch, _countof(szPath));
+    }
+    lstrcpynA(szDebug1, wine_dbgstr_a(szPath), _countof(szDebug1));
+    lstrcpynA(szDebug2, wine_dbgstr_a(szAnswer), _countof(szDebug2));
+    ok(lstrcmpiA(szPath, szAnswer) == 0, "%s vs %s\n", szDebug1, szDebug2);
+}
+
+static void TEST_AssocQueryStringW(void)
+{
+    WCHAR szPath[MAX_PATH], szAnswer[MAX_PATH];
+    CHAR szDebug1[MAX_PATH], szDebug2[MAX_PATH];
+    HRESULT hr;
+    DWORD cch;
+
+    /* ".txt" */
+    lstrcpynW(szPath, L".txt", _countof(szPath));
+    cch = _countof(szPath);
+    hr = AssocQueryStringW(0, ASSOCSTR_EXECUTABLE, szPath, NULL, szPath, &cch);
+    ok_long(hr, S_OK);
+    ExpandEnvironmentStringsW(L"%WINDIR%\\system32\\notepad.exe", szAnswer, _countof(szAnswer));
+    lstrcpynA(szDebug1, wine_dbgstr_w(szPath), _countof(szDebug1));
+    lstrcpynA(szDebug2, wine_dbgstr_w(szAnswer), _countof(szDebug2));
+    ok(lstrcmpiW(szPath, szAnswer) == 0, "%s vs %s\n", szDebug1, szDebug2);
+    ok_int(cch, lstrlenW(szAnswer) + 1);
+
+    /* s_szTextFileW */
+    lstrcpynW(szPath, s_szTextFileW, _countof(szPath));
+    cch = _countof(szPath);
+    hr = AssocQueryStringW(0, ASSOCSTR_EXECUTABLE, szPath, NULL, szPath, &cch);
+    ok_long(hr, S_OK);
+    ExpandEnvironmentStringsW(L"%WINDIR%\\system32\\notepad.exe", szAnswer, _countof(szAnswer));
+    lstrcpynA(szDebug1, wine_dbgstr_w(szPath), _countof(szDebug1));
+    lstrcpynA(szDebug2, wine_dbgstr_w(szAnswer), _countof(szDebug2));
+    ok(lstrcmpiW(szPath, szAnswer) == 0, "%s vs %s\n", szDebug1, szDebug2);
+    ok_int(cch, lstrlenW(szAnswer) + 1);
+
+    /* NON_EXISTENT_FILENAME_W */
+    lstrcpynW(szPath, NON_EXISTENT_FILENAME_W, _countof(szPath));
+    cch = _countof(szPath);
+    hr = AssocQueryStringW(0, ASSOCSTR_EXECUTABLE, szPath, NULL, szPath, &cch);
+    ok_long(hr, S_OK);
+    ExpandEnvironmentStringsW(L"%WINDIR%\\system32\\notepad.exe", szAnswer, _countof(szAnswer));
+    lstrcpynA(szDebug1, wine_dbgstr_w(szPath), _countof(szDebug1));
+    lstrcpynA(szDebug2, wine_dbgstr_w(szAnswer), _countof(szDebug2));
+    ok(lstrcmpiW(szPath, szAnswer) == 0, "%s vs %s\n", szDebug1, szDebug2);
+    ok_int(cch, lstrlenW(szAnswer) + 1);
+}
+
+START_TEST(AssocQueryString)
+{
+    HRESULT hrCoInit = CoInitialize(NULL);
+
+    s_hSHLWAPI = LoadLibraryW(L"shlwapi.dll");
+    s_fnAssocQueryStringA = (FN_AssocQueryStringA)GetProcAddress(s_hSHLWAPI, "AssocQueryStringA");
+    s_fnAssocQueryStringW = (FN_AssocQueryStringW)GetProcAddress(s_hSHLWAPI, "AssocQueryStringW");
+    if (!s_fnAssocQueryStringA || !s_fnAssocQueryStringW)
+    {
+        skip("AssocQueryStringA or AssocQueryStringW not found: %p, %p\n",
+             s_fnAssocQueryStringA, s_fnAssocQueryStringW);
+        return;
+    }
+
+    TEST_Start();
+    TEST_AssocQueryStringA();
+    TEST_AssocQueryStringW();
+    TEST_End();
+
+    FreeLibrary(s_hSHLWAPI);
+
+    if (SUCCEEDED(hrCoInit))
+        CoUninitialize();
+}
diff --git a/modules/rostests/apitests/shlwapi/CMakeLists.txt b/modules/rostests/apitests/shlwapi/CMakeLists.txt
index adba1083be0..4000fd26775 100644
--- a/modules/rostests/apitests/shlwapi/CMakeLists.txt
+++ b/modules/rostests/apitests/shlwapi/CMakeLists.txt
@@ -5,6 +5,7 @@ add_subdirectory(shlwapi_resource_dll)
 include_directories($<TARGET_FILE_DIR:shlwapi_resource_dll>)
 
 list(APPEND SOURCE
+    AssocQueryString.c
     PathFindOnPath.c
     PathIsUNC.c
     PathIsUNCServer.c
diff --git a/modules/rostests/apitests/shlwapi/testlist.c b/modules/rostests/apitests/shlwapi/testlist.c
index 9ec57ee2686..b497fc8836a 100644
--- a/modules/rostests/apitests/shlwapi/testlist.c
+++ b/modules/rostests/apitests/shlwapi/testlist.c
@@ -1,6 +1,7 @@
 #define STANDALONE
 #include <apitest.h>
 
+extern void func_AssocQueryString(void);
 extern void func_PathFindOnPath(void);
 extern void func_isuncpath(void);
 extern void func_isuncpathserver(void);
@@ -16,6 +17,7 @@ extern void func_StrFormatByteSizeW(void);
 
 const struct test winetest_testlist[] =
 {
+    { "AssocQueryString", func_AssocQueryString },
     { "PathFindOnPath", func_PathFindOnPath },
     { "PathIsUNC", func_isuncpath },
     { "PathIsUNCServer", func_isuncpathserver },