A method is described for determining trycyclazole in environmental samples such as river water, soil and animal samples. River water was extracted with dichloromethane and soil was extracted with methanol. Animal material was extracted with benzene after alkali decomposition. The extracts were cleaned up on an alumina column and determined by either GC with flame thermionic detection (FTD) or GC-MS. The proposed method gave a recovery of over 85% and a coefficient of variation of less than 5%, the detection limit being 0.1 ng by both methods. The method was applied to river water, soil and animal samples from a district where aerial spraying had been conducted. No peaks interfering with the determination were observed.