diff --git a/README.md b/README.md
index 0e26223..a751b5a 100644
--- a/README.md
+++ b/README.md
@@ -97,6 +97,7 @@ Eluna API for AC:
 
 ### Group
 - Added `Group:GetGroupType()`: https://github.com/azerothcore/mod-eluna/pull/82
+- Added `Group:SetMemberFlag()`: https://github.com/azerothcore/mod-eluna/pull/102
 
 ### Unit
 - Added `Unit:ModifyThreatPct()`: https://github.com/azerothcore/mod-eluna/pull/25
diff --git a/src/LuaEngine/GroupMethods.h b/src/LuaEngine/GroupMethods.h
index d6fc9d2..763c18a 100644
--- a/src/LuaEngine/GroupMethods.h
+++ b/src/LuaEngine/GroupMethods.h
@@ -428,6 +428,32 @@ namespace LuaGroup
         return 0;
     }
 
+    /**
+     * Sets or removes a flag for a [Group] member
+     * 
+     * <pre>
+     * enum GroupMemberFlags
+     * {
+     *     MEMBER_FLAG_ASSISTANT   = 0x01,
+     *     MEMBER_FLAG_MAINTANK    = 0x02,
+     *     MEMBER_FLAG_MAINASSIST  = 0x04,
+     * };
+     * </pre>
+     * 
+     * @param ObjectGuid target : GUID of the target
+     * @param bool apply : add the `flag` if `true`, remove the `flag` otherwise
+     * @param [GroupMemberFlags] flag : the flag to set or unset
+     */
+    int SetMemberFlag(lua_State* L, Group* group)
+    {
+        ObjectGuid target = Eluna::CHECKVAL<ObjectGuid>(L, 2);
+        bool apply = Eluna::CHECKVAL<bool>(L, 3);
+        GroupMemberFlags flag = static_cast<GroupMemberFlags>(Eluna::CHECKVAL<uint32>(L, 4));
+
+        group->SetGroupMemberFlag(target, apply, flag);
+        return 0;
+    }
+
     /*int ConvertToLFG(lua_State* L, Group* group) // TODO: Implementation
     {
         group->ConvertToLFG();
diff --git a/src/LuaEngine/LuaFunctions.cpp b/src/LuaEngine/LuaFunctions.cpp
index 2dbbb6e..967600f 100644
--- a/src/LuaEngine/LuaFunctions.cpp
+++ b/src/LuaEngine/LuaFunctions.cpp
@@ -1112,6 +1112,7 @@ ElunaRegister<Group> GroupMethods[] =
     { "SetLeader", &LuaGroup::SetLeader },
     { "SetMembersGroup", &LuaGroup::SetMembersGroup },
     { "SetTargetIcon", &LuaGroup::SetTargetIcon },
+    { "SetMemberFlag", &LuaGroup::SetMemberFlag },
 
     // Boolean
     { "IsLeader", &LuaGroup::IsLeader },