Introduction: Up to 70% of patients who undergo radical prostatectomy complain about urine leakage, but persistent stress incontinence 1 year after surgery affects <5% of them. HCl duloxetine is a dual serotonin and norepinephrine reuptake inhibitor that relieves the symptoms of stress urinary incontinence. The purpose of this study was to evaluate the efficacy of HCl duloxetine in the management of urinary incontinence after radical prostatectomy and its impact in urodynamic parameters such as maximal urethral closure pressure (MUCP), abdominal leak point pressure (ALPP) and retrograde leak point pressure (RLPP). Material and Methods: The study included 18 men with stress urinary incontinence 12 months after radical prostatectomy. All underwent a pad test to quantify the degree of urine loss and a urodynamic evaluation before and after a three month treatment with HCl duloxetine. The intrinsic sphincter was evaluated by ALPP and RLPP and the striated sphincter by MUCP. Results: At the pretreatment evaluation the mean ALPP was 52.1 cm H₂O, the mean MUCP was 52.5 cm H₂O and the mean RLPP was 43.1 cm H₂O. After 3 months of HCl duloxetine treatment the mean ALPP was 59.1 cm H₂O, the mean MUCP was 67.3 cm H₂O and the mean RLPP was 45.1 cm H₂O. There was a statistically significant correlation among RLPP, MUCP and ALPP before treatment. After HCl duloxetine treatment there was significant correlation between RLPP and ALPP. Conclusion: The use of HCl duloxetine results in mild increase of MUCP and in significant reduction of urine loss. Its action on the extrinsic sphincter does not provide a complete treatment option for postprostatectomy incontinence.