FIX. RadTreeView - SelectedNode and SelectedNodes should be cleared when the DataSource of the control is set to null test app: using System; using System.Data; using System.Windows.Forms; using Telerik.WinControls.UI; namespace Lab.Tree { public partial class TreeResetSelectionAfterDataSourceIsSetToNull : MainForm { private RadTreeView treeView = new RadTreeView(); public TreeResetSelectionAfterDataSourceIsSetToNull() { InitializeComponent(); treeView.Dock = DockStyle.Fill; treeView.Parent = this; treeView.BringToFront(); DataTable table = new DataTable(); table.Columns.Add("Id"); table.Columns.Add("Name"); table.Rows.Add("1", "name1"); table.Rows.Add("2", "name2"); table.Rows.Add("3", "name3"); treeView.DisplayMember = "Name"; treeView.DataSource = table; treeView.MultiSelect = true; } protected override void OnButton1Click() { Console.WriteLine(treeView.SelectedNodes.Count); Console.WriteLine(treeView.SelectedNode); treeView.DataSource = null; Console.WriteLine("-------------------------------------------"); Console.WriteLine(treeView.SelectedNodes.Count); Console.WriteLine(treeView.SelectedNode); } } }