Since the introduction of serum testing for prostate-specific antigen (PSA) in 1990 for the early detection of prostate cancer, the number of men undergoing a prostate needle-biopsy procedure has increased dramatically. In order to highlight the significance of the various diagnostic outcomes of a prostate needle biopsy, the pathological findings from needle biopsies were compared with those from samples taken during radical prostatectomy and in follow-up biopsies, using data from the 'European randomised screening for prostate cancer' (ERSPC) trial. In men with an elevated PSA value and a benign or negative needle-biopsy result, 10-15% were found to have prostate cancer in follow-up biopsies. In men with a needle-biopsy diagnosis of adenocarcinoma, 29% were found to have questionable histopathological characteristics or minimal cancer that did not require therapy. The incidence of minimal cancer increased to 70% among men with a needle-biopsy diagnosis of focal carcinoma, i.e. a small focus (< 3 mm diameter) of well-differentiated adenocarcinoma, based on one biopsy from a series of six. In men with a needle-biopsy diagnosis of 'suspected malignancy' 36.5% were found to have prostate cancer in follow-up biopsies. In men with a needle-biopsy diagnosis of 'high grade prostatic intra-epithelial neoplasia' 13% were found to have prostate cancer in follow-up biopsies. This percentage was not significantly higher than the percentage of cancers detected after an initially benign biopsy outcome. To avoid over-treatment of a substantial number of men who lack symptoms of prostate cancer but are diagnosed on the basis of biopsy results, it is vital that clinical/pathologic parameters are developed and validated that can help in deciding whether to initiate curative treatment immediately.