hi all i have a sample code this will solve your problem take a form and ToolStripMenuItem from vs toolbox duble click on opentoolstrip and write these code private void openToolStripMenuItem_Click(object sender, EventArgs e) { openToolStripMenuItem.Enabled = false; Form2 frm = new Form2(); frm.MdiParent = this; frm.FormClosed += new FormClosedEventHandler(frm_FormClosed); frm.Show(); } void frm_FormClosed(object sender, FormClosedEventArgs e) { openToolStripMenuItem.Enabled = true; }