Prostate cancer is a slowly progressing but potentially lethal disease. In order to cure it we must detect it while it remains organ confined. Because of the slow course of the disease, prostate cancer screening trials take a long time to show any benefit and in that time the measurement and interpretation of prostate specific antigen (PSA) concentrations have changed, and biopsy and treatment protocols have also developed. Nevertheless, measuring PSA in the blood remains the main tool we have at hand and improvements have been made but not fully utilised. Improvements in the specificity of PSA include age-related PSA reference limits, free to total PSA ratio and PSA dynamics such as doubling time. Improvements in sensitivity have progressed to defining that we should focus on the 50% of men with PSA concentrations above their population median, as men with PSA below the median are very unlikely to develop or suffer from prostate cancer. Like any medical procedure, men should be informed of the risks and benefits but this should ideally be done in a manner that encourages informed choice based on their own understanding and feelings, rather than informed compliance based on the views of others.