The prostate specific antigen (PSA) test clearly provides the opportunity for clinically relevant prostate cancer to be detected at a stage when treatment options are greater and outcomes may be improved. However, in some patients the PSA test may lead to investigations which can identify clinically insignificant cancers which would not have become evident in a man's lifetime. In addition, a raised PSA may often indicate benign prostatic enlargement, and this may provide an opportunity for treatment of this condition before complications develop. The lack of sensitivity and specificity that characterises PSAtesting in the initial diagnosis of prostate cancer largely disappears after treatment of localised prostate cancer, especially after surgery. Three monthly PSA measurement is usually recommended for the first year after primary treatment. Subsequently less frequent testing is required. A PSA rise after primary treatment usually indicates biochemical recurrence and often the need for further therapy. There are two promising urinary RNA biomarkers, prostate cancer antigen 3 (PCA3) and fusion gene TMPRSS2:ERG, both of which aim to distinguish between men with low-risk (indolent) and those with aggressive (clinically significant) cancers. Practitioner. 2016 Apr;260(1792):17-21, 3.