We studied the influence of prostatic massage on the seric levels of acid prostatic phosphatase (PAP) and prostatic specific antigen (PSA) before and 1, 24 and 48 h after the examination. Three groups of patients were studied: 13 patients with prostatic benign hypertrophy (PBH), six patients with metastatic prostate carcinoma and 10 control patients (urinary lithiasis). We observed a significant elevation of both seric markers 1 h after prostatic massage in the PBH and control groups. In both groups, seric marker levels returned to normal values within 24 h with PAP and 48 h with PSA. We recommend to assay serum PSA and PAP with an interval of at least 48 h after rectal digital examination.