Baseline and follow-up data of 54 patients from a single surgical series (1998-2001), who used medicated urethral system for erection (MUSE) for the erectile dysfunction (ED) associated with radical prostatectomy (RP), were obtained. Patients were surveyed using the abridged five-item version of the International Index of Erectile Function (IIEF) questionnaire, commonly referred to as the Sexual Health Inventory of Men (SHIM), to determine presence and severity of ED and efficacy of ED treatment modalities. The mean patient age was 63.7+/-5.6 y and the mean follow-up period was 2.3+/-1.2 y. All patients experienced ED for at least 6 months after their surgery before starting MUSE therapy. Overall, 55% of the patients achieved and maintained erections sufficient for sexual intercourse while on MUSE and 48% continued long-term therapy with a mean use of 2.32+/-1.2 y. The mean presurgery SHIM score in these patients was 19.2+/-1.3, which decreased to 5.2+/-0.5 after surgery and increased to 16.3+/-1.3 after MUSE treatment. A total of 28 patients (52%) discontinued treatment after a mean use of 8+/-1.4 months. The reasons for discontinuation were insufficient erections (n = 16, mean SHIM score of 10.5+/-4.4), switch to other ED therapies (n = 4), natural return of erections (n = 4) and urethral pain and burning (n = 4). Excluding the patients (n = 8) who preferred other therapies and return of natural erections, the compliance to MUSE was 63%. There were no significant differences in the IIEF-5 responses between the patients who had a nerve-sparing technique (n=34) and those who did not (n = 20) or among patients who used different doses (250, 500 or 1000 microg) of MUSE. The results of the current trial indicate that MUSE is a successful treatment option in RP patients with established ED. It appears that a post-treatment SHIM score of > or = 16 defines a successful outcome with MUSE therapy.