Exposure to pesticides is a serious environmental problem, since a realm of uncertainty exists concerning the toxic effects on man. Due to economical and more efficacious reasons, pesticides are being used in combination. The use of pesticides in combination, especially carbaryl and malathion, has become increasingly prevalent in recent years. Carbaryl and maiathion in combination are known to distribute to the rat liver and kidney to a greater extent than when exposure is limited to either pesticide alone. Since, carbaryl or malathion as individual pesticides are known to react with glutathione (GSH) during their metabolism and alterations in rat blood and liver GSH content after subacute exposure to this combination were noted in earlier work from this laboratory, it is important to examine the glutathione related parameters in the rat liver and kidneyin vitro.