Pythonの2系では，3系と違い，tkinterではなく，Tkinter．

$ /usr/bin/python2.7 ./test_tkinter.py
> Traceback (most recent call last):
> File "./test_tkinter.py", line 2, in
> from tkinter import *
> ImportError: No module named tkinter

$ /usr/bin/python3.4 ./test_tkinter.py
# GUIが表示される．

参考: wiki
"Note: As of Python 3.0, Tkinter and related modules were replaced by the tkinter package."
とある．

2系で動かしたい場合．
$ vi ./test_tkinter.py
-- from tkinter import *
++ from Tkinter import *