how to close form1 when i open form2?

[RudiVisser]

It does not work. It will close both form because this code must be in Button_Click of form1 so that when you call This.Close() --> form1 will be Close with all of this code will be close, too.

Any ideas?

this.Hide();
Form2 newform = new Form2();
newform.Show();

This way the form's still open (in theory), however calling application.exit(); to close everything, will close that form too.