Abstract: GC was applied to the determination of methamidophos in water. The water sample (50.00 mL) was evaporated to near dryness by rotary evaporator and extracted thrice with 5 mL of ethyl acetate in each extraction. The extracts were combined and concentrated to 1 mL in an evaporation tube. The solution was separated on HP-1701 capillary column and detected by FPD. Linear relationship between values of peak area and mass concentration of methamidophos was kept in the range of 0.050-1.00 mg·L-1 with detection limit (3S/N) of 0.001 mg·L-1. Tests for recovery were made by standard addition method at 3 concentration levels, giving values of recovery and RSD′s (n=5) in the ranges of 84.0%-91.2% and 3.4%-5.9% respectively.