Since the route of administration of BCG may have an important function in immunotherapy, we investigated intralymphatic administration to direct BCG to the lymph nodes. Multiple injections of high doses of BCG were administered to 6 rhesus monkeys via the dorsal lymphatics of the lower limb. A suppurative lymphadenitis was observed along the lower limb and in the inguinal area in 5 of the 6 monkeys. However, many of the complications reported with other routes of administration were not observed. Granulomatous reactions and histiocytic responses developed in lymph nodes on the injected sides of the pelvis and distant nodes as well as in the liver. The intralymphatic route is the method by which high doses of nonspecific immunostimulants were delivered to regional lymph nodes. The efficacy of this approach remains to be established in tumor-bearing animals and humans.