Primary cultures of 48 cases of prostate carcinoma were established. The expression of cytokeratin and prostate specific antigen were determined in the cultures routinely. G-banding analysis revealed some clonal numerical and structural aberrations: Trisomy 7 occurred in 4 cases, in one case in combination with a t(Y;22). Loss of the Y chromosome was found in 3 cases, in one case in combination with gain of chromosome #5. The most frequent clonal structural aberration var9(qh) occurred in 6 cases. A deletion of 6q(23) was found in two cases. None of these aberrations were found in normal tissue of the same patients. Numerical changes were demonstrated by fluorescence in situ hybridization (FISH) on native tissue, confirming the conventional cytogenetic findings.