Abstract: During the cotton growing periods of 2009-2010, soil samples were collected from the rhizospheres of cottons of SGK321 (Bt/CpTI-transgenic cotton) and Shiyuan 321,seed parent of the former,as control,in cotton fields that had long been cultivated with that respective variety of cotton,in Jiujiang of Jiangxi,Xinxiang of Henan and Kashi of Xinjiang,three major cotton production areas of China,in the Yangtze River Valley,Yellow River Valley and the inland of Northwest China,respectively,for monitoring of dynamics of Cry1Ab protein residuals in the rhizospheres,using the enzymelinked immunosorbent assay (ELISA).Results show that Cry1Ab protein content was significantly higher in soil samples collected from SGK321 cotton fields at the budding,flowering and boll bearing stages than in those from Shiyuan 321 cotton fields,but no significant difference was found between the two collected at the maturing stage.The findings indicate that long-term cultivation of Bt/CpTI-transgenic cotton would not lead to accumulation of Cry1Ab protein in the cotton rhizospheric soil.