The biochemical markers alkaline phosphatase (Alk P), prostatic acid phosphatase (PAP) and prostate-specific antigen (PSA) were measured 3-monthly in 61 patients with disseminated prostatic cancer who were treated with LHRH analogues. The decrease in Alk P and PSA during the first 6 months of treatment was significantly related to a better survival. In this follow-up study, only PSA was useful for monitoring prostatic cancer during hormonal treatment. Before it was visible on a bone scan, PSA gave an indication of tumor progression. PSA might permit omission of routine bone scanning. Consensus must be obtained about the cost-saving use of biochemical markers in the treatment of disseminated prostatic cancer. With the number of treatment options increasing, objective measures are of utmost importance. Biochemical markers can be used for prognosis and monitoring of the treatment of patients with disseminated prostatic cancer.