The presence of chromosomal aberrations (CA) in starved Wistar rats given organosphosphorus pesticides (OP), methyl parathion [O,O-diethyl-O (p-ni-trophenyl)-phosphothioate] (MP) and monocrotophos [O,O-dimethyl-O (2-methyl-carbamoyl-1-methylvinyl) -phosphate](MCP) was investigated. The rats were starved for 4 days, and then exposed to a single dose of MP technical orally once at a dose of 0.06 mg/kg body weight, or to MCP technical orally once at a dose of 0.5 mg/kg body weight for a period of 24 h. Rats in the control group, with and without pesticide exposure, were also simultaneously studied. All animals were sacrificed on completion of 5th day of starvation, bone marrow cells were processed for chromosome analysis and mitotic indices. Starved rats presented elevated CA frequency compared to the control (untreated) group. The CA frequency was unaffected by the administration of MP but was accentuated by MCP treatment in starved rats. Further, all the three groups, starved and starved pesticide treated, recorded significantly low mitotic indices.