An experiment was conducted to determine the capability of isoprinosine (ISO) and levamisole (LEV) to augment delayed-type hypersensitivity and lymphocyte blastogenic reactions in artificially reared pigs. Sow-reared pigs (n = 15) were kept with their dams; artificially reared pigs (n = 15) were removed from sows within 2 days after parturition and reared artificially for 21 days. Isoprinosine was administered orally (75 mg/kg/day) from days 0 to 10. Levamisole (2 mg) was injected subcutaneously on days 5 and 10. Control pigs were given distilled water orally from days 0 to 10 and injected subcutaneously with 0.15M NaCl on days 5 and 10. Lymphocyte proliferative responses to phytohemagglutinin, concanavalin A, and pokeweed mitogen were evaluated at week 2. The phytohemagglutinin skin-test responses were evaluated in all pigs at weeks 1 and 3 of the trial. Hematologic values, body weight, and mortality were evaluated each week. The skin-test responses and mitogen-induced lymphocyte proliferative responses were lower (P less than 0.05) in artificially reared controls when compared with responses in sow-reared pigs. However, ISO and LEV enhanced (P less than 0.05) the responses in the artificially reared pigs to values comparable with those of the sow-reared controls. Body weight was greater (P less than 0.01) in sow-reared pigs than in artificially reared pigs; drug treatment did not influence weight gain. These data indicated that immunopotentiation of the cellular immune responsiveness of artificially reared pigs may be possible with ISO or LEV.