An Easy Way to Find All Open Forms in VB.NET

 Dim frm As Form

            For Each frm In My.Application.OpenForms

                If frm Is My.Forms.TheFormINeed Then
                  'do something
end if

 Dim frm As Form

    Dim NameToSearch As String

    NameToSearch = "frmMyForm"    ' name of the form I have to look for

    For Each frm in Forms

        If frm.Name = NameToSearch Then

            ' VB has found a form with that name in the collection

            ' it means the form is loaded already

            ' ..... your code here ....

            Exit For

        End If

    Next frm 

PublicClassTheFormThatOpensAnotherForm

InheritsForm

Private_formAsFormThatThisFormOpens=Nothing

PublicSubbutton1_Click(ByValsenderAsObject,ByValeAsEventArgs)

'performsomework

If_formIsNotNothingAndAlsoNot_form.IsDisposedAndAlso_form.VisibleThen

EndIf

EndSub

PublicSubOpenForm()

If_formIsNotNothingAndAlsoNot_form.IsDisposedThen

_form.Show()

Else

_form=NewForm()

_form.Show()

EndIf

EndSub

EndClass Private Sub button1_Click(sender As Object, e As EventArgs) Dim open As Boolean = True For Each frm As Form In MdiChildren If frm.[GetType]() = GetType(Form1) Then open = False End If Next If open Then Dim frmOne As New Form1() frmOne.MdiParent = Me frmOne.Show() Else MessageBox.Show("Form1 is already open") End If End Sub Private Sub button2_Click(sender As Object, e As EventArgs) Dim open As Boolean = True For Each frm As Form In MdiChildren If frm.[GetType]() = GetType(Form2) Then open = False End If Next If open Then Dim frmTwo As New Form2() frmTwo.MdiParent = Me frmTwo.Show() Else MessageBox.Show("Form2 is already open") End If End Sub Private Function CheckIfOpen(ByVal frmName As String) As Boolean Dim frm As Form For Each frm In Me.MdiChildren If frm.Name = frmName Then frm.Focus() Return True Exit Function End If Next Return False End Function