Although PSA is a most valuable tool for the practicing physician, it lacks sufficient sensitivity and specificity for detecting early prostate cancer to be the perfect tumor marker. The parameters PSAD and PSA velocity are useful attempts to make PSA a better tumor marker, but they likewise are not always reliable on an individual basis. There is now evidence from several investigations that the serum PSA concentration in healthy men without clinical evidence of prostate cancer increases with advancing age. This is primarily attributable to the concomitant increase in prostate size over the same time period. As a result, age-specific reference ranges have been determined and have the potential to make PSA a more sensitive tumor marker for men less than 60 years of age and a more specific tumor marker for men beyond 60 years of age. If one utilizes the age-specific reference ranges for serum PSA, it appears that PSAD can be eliminated as a parameter in the diagnostic evaluation of patients suspected of having prostate cancer. Thus, a new algorithm utilizing age-specific reference ranges has been developed.