OBJECTIVE: To evaluate the efficacy of preoperative pelvic floor muscle training (PFMT) on histomorphometry, muscle function of patients undergoing radical prostatectomy (RP). METHODS. A prospective intervention clinical study was designed in 16 patients. The intervention group (n=8) received a training session with PFMT supervised, three times a day, three session for week, 30 days before the PR. The control group (n=8) received oral and written instructions to be performed at home (lifestyle modifications). Before and after the intervention was evaluated muscle function of the external urethral sphincter and contraction pressure of the levator ani. At the end of the intervention and day of the surgery, muscular tissue samples residual external sphincter muscle of urethra for histomorphometric analysis. RESULTS. After the intervention, participants who performed PFMT showed increased cross-sectional area of the muscle fibers of the external urethral sphincter (1313±1075 µm² vs. 1056±844 µm², p=0.03) and higher pressure contraction of the levator ani (F=9.188, p=0.010). CONCLUSIONS. Early PFMT induces changes in the histology and function of the pelvic floor muscles. These results provide new evidence of the benefit of PFMT in preventing complications associated with the PR.