Lymphocytic infiltration of melanomas represents an immunological response of the organism to the tumor. In order to establish the prognostic significance of this parameter, 369 cases of malignant choroidal melanoma were investigated in the study reported here with respect to the degree of infiltration. The relationship to survival time and other histopathological parameters was examined by means of the mortality tabulation method. The 84.5% five-year survival rate among patients with melanomas exhibiting intense infiltration was significantly higher than the 70.9% rate among patients with tumors showing little infiltration. This study statistically confirms current conjecture that the degree of lymphocytic infiltration, already proven to be prognostically significant in cutaneous melanoma, is also prognostically significant in choroidal melanoma. No correlations to other histopathological parameters could be demonstrated.