Among 27 uveal melanomas, five were found to contain tumor infiltrating lymphocytes (TILs). Four had high levels of lymphocytes, and the fifth had comparatively low levels but adequate numbers for comprehensive analysis. The TILs were analyzed by flow cytometry to determine the relative proportions of lymphocyte subsets and markers of lymphocyte activation. The results show the predominance of T-suppressor/cytotoxic lymphocytes and insignificant levels of B-cells present in the infiltrate. The T-suppressor/cytotoxic cells were generally activated to a higher degree than the T-helper cells when assayed for levels of the histocompatibility antigen, HLA-DR. T-helper cells expressed more interleukin (IL-2) receptor (Tac) than T-suppressor/cytotoxic cells.