Sub test()
If Sheets("activités").Range("B2") = FAUX Then
For i = 4 To Range("B65535").End(xlUp).Row
If Cells(i, 2).Value = "activité 1" Then
Rows(i).Hidden = True
End If
Next i
Else
For i = 4 To Range("B65535").End(xlUp).Row
If Cells(i, 2).Value = "activité 1" Then
Rows(i).Hidden = False
End If
Next i
End If
End Sub