import Tkinter
MyRoot = Tkinter.Tk()
MyRoot.state("zoomed")
MyRoot.mainloop()
root = Tk()
w, h = root.winfo_screenwidth(), root.winfo_screenheight()
root.geometry("%dx%d+0+0" % (w, h))
root = Tk()
# for Ubuntu
root.attributes('-zoomed', True)
# for Windows
root.state('zoomed')