Objective: p53 and androgen receptor gene changes and bcl-2 expression in prostatic intraepithelial neoplasia (PIN) and adenocarcinoma were studied. The genetic associations of PIN and adenocarcinoma as detected by F1SH and immunohistochemistry were discussed. Material and Method: The study group consisted of 18 prostate cancer cases treated by radical prostatectomy. The p53 and androgen receptor gene changes at chromosomal level were studied usi'ng the FISH technique. Also, immunohistochemistry was used to search for bcl-2 expression. Results: Of the 18 cases studied by FISH, it was found that in benign areas AR gene amplification was 78% (14/18) and 100% disomy with wild type p53, in PIN areas AR gene amplification was 33% (6/18), p53 amplification 28% (5/18), in carcinomas AR gene amplification was 39% (7/18), and p53 amplification 28% (5/18). We observed the bcl-2 immunexpression mainly in basal ductal cells in benign, PIN and carcinoma areas. Conclusion: The results of our study suggest that AR gene amplification is significantly higher in benign areas compared to carcinomatous foci and that the presence of AR gene amplification is associated with the tumour stage. PIN is the most likely precursor of prostatic carcinoma