The aim of this study was to investigate by an in situ hybridization procedure the Telomerase expression as a marker in prostate cancer and to correlate these results with several prognostic factors concerning this cancer. Imprint smear samples were obtained from 70 prostates removed from patients who underwent radical prostatectomy for prostate adenocarcinoma. Telomerase expression in cancerous prostate smears was studied using an in situ hybridization procedure. The results were correlated with prognostic factors such as pathologic staging, Gleason grading, PSA serum levels and tumour differentiation. Positive Telomerase expression was detected in 88.6% prostate cancer smears. Telomerase expression was significantly correlated with the Gleason score (p < 0.001), tumour differentiation (p < 0.001) and PSA serum levels (p = 0.002). The distribution of Telomerase expression according to histopathological staging was not statistically significant (p < 0.56). In conclusion Telomerase expression could be a marker indicating the malignant potential of prostate cancer.