The aim of this study was twofold: 1) to estimate the prevalence of the GSTM1, GSTT1 and GSTP1 gene polymorphisms in the Slovak population of men and compare those results with the respective data published by other groups (GSEC project – Genetic Susceptibility to Environmental Carcinogens); and 2) to evaluate the frequencies of the GSTT1 and GSTM1 null genotypes and polymorphisms in GSTP1 also in the patients with prostate cancer in order to compare the evaluated proportions with those found in the controls. The gene discussed is GSTM1; the disease is Familial prostate cancer.