This study was conducted over the 19 mo from 1- Mar -2008 to 1-Nov-2009 in Mycology Laboratory, School of Public Health, Tehran University of Medical Sciences, and Scientific and Research Laboratory of Farogh, Tehran, Iran. The sample size of 275 was calculated by considering a 95% confidence interval and 0.06 study accuracy based on the previous similar performances (23 and unpublished data). This investigation was done on totally 275 imported rice samples (5kg each) that were randomly purchased and collected from the markets in Tehran, Iran according to method of the Iranian national standards of to assess aflatoxin existence rate and affect of CA treatment on the contaminated ones. Rice samples were stored in zip-locked plastic bags at 4оC until being sampling for aflatoxin analysis in agricultural products (24).