Adult female B6C3F1 mice received distilled water only or water containing 1.0, 10, or 100 ppb of aldicarb daily for 34 days. The target concentration of aldicarb present in the 100 ppb dosing solution was analytically verified. To further develop an immune profile of this compound, following aldicarb exposure, the ability of splenic natural killer cells and specifically sensitized cytotoxic T-lymphocytes to lyse YAC-1 lymphoma and P815 tumor cells, respectively, was evaluated. To supplement the functional assays, the impact of aldicarb exposure on the percentages and absolute numbers of total T-cells, T-suppressor, T-helper, and B-cells was evaluated. The absence of statistically significant effects on any of these parameters supports earlier reports that aldicarb does not result in adverse effects on the immune system of mice.