The disposition and metabolism of pesticides used in combination, especially carbaryl and malathion, is of considerable toxicological importance. Radioactivity was rapidly absorbed from the rat gastrointestinal tract (GIT) following the administration of 0.25 ml of 10 mg/kg [14C]carbaryl (0.80 μCi), 10/10 mg/kg [14C]carbaryl/malathion (0.80 μCi), 10 mg/kg [14C]malathion (1.03 μCi), or 10/10 mg/kg [14C]malathion/carbaryl (0.86 μCi). The administration of carbaryl or malathion, individually and in combination, followed a two‐phase elimination model. The presence of malathion decreased the rate constants of absorption and β‐phase elimination of [14C]carbaryl. In the mean time, the length of the distribution phase and the area under the curve of [14C]carbaryl were decreased by malathion administration. Although [14C]malathion's absorption half‐life was unchanged in the presence of carbaryl, increases were noted in the length of the distribution phase, β‐phase elimination half‐life, and area under the curve for malathion when administered simultaneously with carbaryl.