A simple and efficient method for the determination of organotin compounds ( OTCs) in biota by GC-MS coupling with sodium tetraethylborate ( NaBEt4 ) derivatization was established. The results showed that recoveries for each OTCs spiked in blank freeze-dryed biological samples ( 0 . 1 g ) following extraction (15 mL 0. 035 mol/L methanolic HCl solution for 1 h ) and derivatization (2 mL contained internal standard n-hexane and 0. 5 mL of 2% (m/V) NaBEt4 solution for 30 min) were above 80%. The method is fast and easy to operate for the determination of OTCs in complex biological samples. The minimum limit of detection was about 0. 01 μg/L, and relative standard deviation values were within 10% for three parallel samples.