Question

Possible Duplicate:
How to avoid multiple instances of windows form in c#

I want to show open form only once in an application without creating them as MDI form.

Answer 1

Before opening the form from your code, check the Application.OpenForms property and see if the form exists in the collection.

Something like:

if ((Application.OpenForms["Form1"] as Form1) != null)
{
 //Form is already open
}
else
{
// Form is not open
}