The immunotoxic effect of diazinon, carbofuran and cypermethrin was evaluated in female BALB/C mice. Mice were dosed by gavage with 0.01, 0.001 and 0.0001 of the oral LDso of each technical insecticide. The lymphocyte proliferation assays were used to measure the functional activity of thymus-dependent (T-cells) and bursal equivalent (B-cells) lymphocytes by concanavalin A (con A) or lipopolysacharide (LPS). Mitogenesis or cell proliferation was measured by tritiated thymidine (H) incorporation. Results reveal, no changes in body weight except with the high dose of cypermethrin. Reduction in spleen cellularity and weight of intoxicated mice were recorded. In addition the mixed lymphocyte reaction (MLR) of the spleenic cells was changed. Lymphocyte proliferative reponses to Concanavalin A (con A) and Lipoplysaccharide (LPS) were also reduced in spleenocytes.