This research aims to evaluate the presence and distribution of pesticides in Babolrood River of Mazandaran Province in Iran. Mean diazinon levels in surface water ranged from 77.6 to 101.6 μg L(-1) with maximum level of 768.9 μg L(-1) and mean malathion levels ranged from 55.7 to 75.9 μg L(-1) with maximum level of 506.6 μg L(-1). The residues of malathion and diazinon pesticides in all of the stations, 2 weeks after spraying, were more than allowed limits.