To assess the efficacy of vacuum constriction devices (VCD) following radical prostatectomy (RP) and determine whether early use of VCD facilitates early sexual activity and potentially earlier return of erectile function. This prospective study consisted of 109 patients who underwent nerve-sparing (NS) or non-nerve-sparing (NNS) RP between August 1999 and October 2001 and developed erectile dysfunction following surgery. The patients were randomized to VCD use daily for 9 months (Group 1, N=74) or observation without any erectogenic treatment (Group 2, N=35). Treatment efficacy was analyzed by responses to the Sexual Health Inventory of Men (SHIM) (abridged 5-item International Index of Erectile Function (IIEF-5)), which were stratified by the NS status. Patient outcome regarding compliance, change in penile length, return of natural erection, and ability for vaginal intercourse were also assessed. The mean patient age was 58.2 years, and the minimum follow-up was 9 months. Use of VCD began at an average of 3.9 weeks after RP. In Group 1, 80% (60/74) successfully used their VCD with a constriction ring for vaginal intercourse at a frequency of twice/week with an overall spousal satisfaction rate of 55% (33/60). In all, 19 of these 60 patients (32%) reported return of natural erections at 9 months, with 10/60 (17%) having erections sufficient for vaginal intercourse. The abridged IIEF-5 score significantly increased after VCD use in both the NS and NNS groups. After a mean use of 3 months, 14/74 (18%) discontinued treatment. In Group 2, 37% (13/35) of patients regained spontaneous erections at a minimum follow-up of 9 months after surgery. However, only four of these patients (29%) had erections sufficient for successful vaginal intercourse and rest of patients (71%) sought adjuvant treatment. Of the 60 successful users, 14 (23%) reported a decrease in penile length and circumference at 9 months (range, 4-8 months) compared to 12/14 (85%) among the nonresponders. However, in control group 22/35 reported decrease in penile length and circumference. Early use of VCD following RP facilitates early sexual intercourse, early patient/spousal sexual satisfaction, and potentially an earlier return of natural erections sufficient for vaginal penetration.