diff --git a/src/controllers/groups_controller.rs b/src/controllers/groups_controller.rs
index 934cd28..5dcbd1f 100644
--- a/src/controllers/groups_controller.rs
+++ b/src/controllers/groups_controller.rs
@@ -13,6 +13,7 @@ use crate::constants::{DEFAULT_GROUP_LOGO, PATH_GROUPS_LOGOS};
 use crate::controllers::routes::RequestResult;
 use crate::data::group::{Group, GroupAccessLevel, GroupPostsCreationLevel, GroupRegistrationLevel, GroupVisibilityLevel};
 use crate::data::group_id::GroupID;
+use crate::data::group_member::GroupMembershipLevel;
 use crate::data::http_request_handler::HttpRequestHandler;
 use crate::data::new_group::NewGroup;
 use crate::helpers::{groups_helper, virtual_directory_helper};
@@ -159,5 +160,16 @@ pub fn get_members(r: &mut HttpRequestHandler) -> RequestResult {
 
 /// Invite a user to join a group
 pub fn invite_user(r: &mut HttpRequestHandler) -> RequestResult {
-    r.success("Ready to implement")
+    let group_id = r.post_group_id_with_access("group_id", GroupAccessLevel::MODERATOR_ACCESS)?;
+    let user_id = r.post_user_id("userID")?;
+
+    if groups_helper::get_membership_level(&group_id, Some(user_id.clone()))? != GroupMembershipLevel::VISITOR {
+        r.bad_request("The user is not a visitor of the group!".to_string())?;
+    }
+
+    groups_helper::send_invitation(&group_id, &user_id)?;
+
+    // TODO : send a notification
+
+    r.success("The user has been successfully invited to join the group!")
 }
\ No newline at end of file
diff --git a/src/helpers/groups_helper.rs b/src/helpers/groups_helper.rs
index 659782b..ad175a3 100644
--- a/src/helpers/groups_helper.rs
+++ b/src/helpers/groups_helper.rs
@@ -331,6 +331,18 @@ pub fn get_list_members(g: &GroupID) -> ResultBoxError<Vec<GroupMember>> {
         .exec(db_to_group_member)
 }
 
+/// Send an invitation to a user
+pub fn send_invitation(group_id: &GroupID, user_id: &UserID) -> ResultBoxError {
+    insert_member(&GroupMember {
+        id: 0,
+        user_id: user_id.clone(),
+        group_id: group_id.clone(),
+        time_create: time(),
+        level: GroupMembershipLevel::INVITED,
+        following: true,
+    })
+}
+
 /// Turn a database entry into a group struct
 fn db_to_group(row: &database::RowResult) -> ResultBoxError<Group> {
     let group_id = row.get_group_id("id")?;