Snails Lymnaea accuminata, were exposed to 2.8 mg/l (1/10th of 96 hrLC50) and 5.6 mg/l(1/5th of 96hr LC50) of insecticide Phytofos. Initially at 24 hours, at both the concentrations decrease in oxygen consumption rate is noted. At 48 hours stage, an increase in oxygen consumption rate is noticed at both the sublethal concentrations. At 72 hours stage in both the sublethal concentrations reduction in oxygen consumption is noted. At the end of 96 hours, again in both the concentration decrease in oxygen consumption prevailed. These experimental snails upon transfer to fresh water for 24 hours, showed recovery in oxygen consumption rate. Oxygen consumption rate are discussed with respect to sublethal concentration and time of exposure to toxicant Phytofos.