Prostate-specific antigen (PSA) velocity predicts the presence of prostate cancer on biopsy and a greater risk of prostate cancer death after radical treatment. A new variation on PSA velocity called the risk count was recently shown to provide incremental reclassification for intermediate to high-grade disease on biopsy beyond PSA and age. These markers therefore have the potential to reduce overdiagnosis and overtreatment of indolent prostate cancer, and several professional guidelines support the use of PSA kinetics along with other predictors as part of the diagnostic algorithm. Among men already diagnosed with prostate cancer, PSA kinetics may also be helpful in predicting prognosis after definitive therapy.