To workaround this issue you should dispose the Instance property of RadMessageBox after each show of message box. For example: WORKAROUND: RadMessageBox.Show("Text"); RadMessageBox.Instance.Dispose(); If you are using themes, consider the following approach: RadMessageBox.SetThemeName("Windows7"); RadMessageBox.Show("This is some long text that sometimes does not wrap as it should."); var field = typeof(RadMessageBox).GetField("radMessageBoxForm", BindingFlags.NonPublic | BindingFlags.Static); field.SetValue(null, null);