Familial occurrence belongs to factors followed in etiology and pathogenesis of testicular germ-cell tumors. Association with abnormal testicular development, or with other risk factors is relatively frequent. In our material 650 patients had been treated for testicular cancer in the period of 1981-1995. Familial occurrence was observed 7-times (1.08%), most frequently in combination with cryptorchidism. Individual families were analyzed in details, including HLA typing. On basis of the observations the supplementation of initial examination of each patient with suspicious testicular cancer with detailed familial history aimed also at the occurrence of urogenital developmental anomalies and tumors has been recommended. The knowledge about familial tumor occurrence in the first-degree relatives in combination with thorough testicular self-examination is being considered of great importance in the secondary prevention.