A case of familial testicular malignancy in a father and his son is reported. This represents the seventh described case of father-son testicular cancer. The father had seminoma and the son had teratocarcinoma. Both patients' peripheral blood lymphocytes were tested for 52 HLA specificities: the father's antigens were HLA A3, B13, B14, Cw6, Cw8 and the son's were HLA A2, A3, B14, Cw8. (Common haplotype: A3, B14, Cw8). The association between HLA antigens and testicular cancer is discussed.
