I have one Azure AD group named Demo with below group members: When I ran below graph query in Graph Explorer by filtering with mail, I too got null results for members: GET https://graph.microsoft.com/beta/groups?$filter=mail+eq+ demo@xxxxxxxxx.onmicrosoft.com +&$select=displayName,mail,members Response: Note that, you need to use $expand parameter in the query to get members of group. To confirm that, you can check this MS Doc for reference. When I ran below modified query by including $expand parameter, I got group members too in response like below: GET https://graph.microsoft.com/beta/groups?$filter=mail+eq+ demo@xxxxxxxxx.onmicrosoft.com +&$select=displayName,mail,members&$expand=members($select=id,displayName) Response: To get the same via code, I registered one Azure AD application and granted below API permissions in it: Now, I ran below c# code to get group members Ids in the response like below: using Azure.Identity; using Microsoft.Graph; using Microsoft.Graph.Models; using Microsoft.Kiota.Abstractions; using Microsoft.Graph.Models.ODataErrors; using System; var scopes = new[] { "https://graph.microsoft.com/.default" }; var clientId = "appId"; var tenantId = "tenantID"; var clientSecret = "secret"; var options = new ClientSecretCredentialOptions { AuthorityHost = AzureAuthorityHosts.AzurePublicCloud, }; var clientSecretCredential = new ClientSecretCredential( tenantId, clientId, clientSecret, options); var graphClient = new GraphServiceClient(clientSecretCredential, scopes); try { var result = await graphClient.Groups.GetAsync((requestConfiguration) => { requestConfiguration.QueryParameters.Filter = "mail eq demo@M365x56209219.onmicrosoft.com "; requestConfiguration.QueryParameters.Select = new string[] { "displayName", "mail", "members" }; requestConfiguration.QueryParameters.Expand = new string[] { "members" }; }); Console.WriteLine("Group info:"); foreach(var group in result.Value) { Console.WriteLine(group.DisplayName); Console.WriteLine(group.Mail); Console.WriteLine(" Group Members:"); foreach (var member in group.Members) { Console.WriteLine(member.Id); } } } catch (ODataError odataError) { Console.WriteLine(odataError.Error.Code); Console.WriteLine(odataError.Error.Message); } Response: