disabling/greying a treeview node

A simple solution that may do what you want is to simply set the ForeColor of the node you want greyed to Color.Gray or Color.LightGray. You can then handle the BeforeSelect event of the treeview and check for the fore color, if it is Color.Gray or Color.LightGray, depending on which you choose, set the Cancel property of the TreeViewCancelEventArgs to true: private void treeView1_BeforeSelect(object sender, System.Windows.Forms.TreeViewCancelEventArgs e) { if(e.Node.ForeColor == Color.Gray) { e.Cancel = true; } }