Human telomerase acts to maintain functioning telomeres, which are required for cellular immortality and very likely for cancer progression. Telomerase activity is present in about 85% of human cancers tested, but it has not been found in most human somatic cells and tissues. We used the Telomeric Repeat Amplification Protocol to perform telomerase activity assays on sextant needle core samples obtained from 35 freshly excised radical retropubic prostatectomy specimens. Similar assays were done on prostatic tissues obtained by means of other urologic procedures from 8 patients without prostate cancer. Telomerase activity was found in one or more specimens from 32 of 35 prostate cancer patients (91%), but was not detectable in all biopsy specimens from 7 of 8 cancer-free patients (88%). Further analysis showed that cancers more poorly differentiated, with higher Gleason scores, were always associated with a higher rate of telomerase detection and stronger telomerase activity. Moreover, comparison of telomerase activity in needle core samples with the volume of cancer in surrounding tissue as observed on corresponding histologic slides showed that stronger activity was positively correlated with a higher cancer volume. Prognostic indicators of prostate cancer and the expression of telomerase appear to be linked. The presence of telomerase activity in prostate tissue may aid in the detection of prostate cancer and produce additional prognostic information.