Upon inoculation of highly metastatic ESb lymphoma cells into the ear pinna of syngeneic mice a potent specific antitumor immune response is induced which prevents the outgrowth of the tumor cells at this particular site. When the tumor cell inoculated pinna was resected at different times after antigen application, systemic protective antitumor immunity, tested by s.c. tumor challenge 7 days later, could still be induced. This was true even for a situation in which the pinna was resected as early as two hours after tumor cell inoculation. Protective antitumor immunity was found to be even augmented when the pinna was removed three days after tumor cell inoculation as compared to the non-resected situation. Pinna resection had no effect on the induction of a tumor specific cytotoxic T lymphocyte response while resection after 48 h had an augmenting effect on the delayed type hypersensitivity (DTH) response. An explanation for some of these findings was found when lacZ-labeled lymphoma cells were used for single cell detection in tissue sections. As early as 15 min after intra-pinna inoculation disseminated single tumor cells were detected in the local draining lymph node as well as in the spleen. Whether these tumor cells can prime T cells for protective immunity directly or only after processing and presentation by specialized host cells remains to be elucidated.