diff --git a/quantecon/estspec.py b/quantecon/estspec.py
index 3700f7bb9..ed8f65ae9 100644
--- a/quantecon/estspec.py
+++ b/quantecon/estspec.py
@@ -10,7 +10,6 @@
 from __future__ import division, print_function
 import numpy as np
 from numpy.fft import fft
-from pandas import DataFrame
 import statsmodels.api as sm