The aims of this study were to compare 12-week outcomes of single-therapy tolterodine (Detrol LA) extended release to intravaginal estrogen (Estrace) for overactive bladder (OAB) symptoms and characterize 24- and 52-week outcomes in women undergoing combined therapy. A single-site randomized, open-label trial in women with urinary frequency, urgency, nocturia, and/or urgency urinary incontinence symptoms was performed. Fifty-eight participants were randomized to oral tolterodine extended release daily or intravaginal estradiol cream nightly for 6 weeks then twice per week. The primary outcome was change in Overactive Bladder Questionnaire (OAB-q) symptom bother score at 12 weeks. Secondary outcomes included the Health-Related Quality of Life Questionnaire (HRQL) of the OAB-q and a 3-day bladder diary. At 12 weeks, subjects were offered addition of the alternative therapy with follow-up at 24 and 52 weeks. There was no difference in symptom bother score improvement between the tolterodine and intravaginal estradiol groups baseline to 12 weeks (20.6 ± 21.7, -15.8 ± 23.3, respectively, P = 0.45). There was a significant within-group decrease in symptom bother score from baseline to 12 weeks (tolterodine, P < 0.0001, and intravaginal estradiol, P = 0.002). Secondary outcome improvement within groups was noted in the HRQL total, urinary incontinence episodes, and median voiding frequency (all P ≤ 0.03) in the tolterodine group and in the HRQL total score (P = 0.03) in the intravaginal estradiol group, with no differences between groups. Combined therapy outcomes at 24 and 52 weeks compared with single therapy at 12 weeks revealed significant improvement in symptom bother score in the intravaginal estradiol + tolterodine group at 24 and 52 weeks (20.0 ± 23.9, P = 0.008; -16.7 ± 23.3, P = 0.02, respectively). Significant within-group improvement in OAB-q symptom bother was noted in both the intravaginal estradiol and tolterodine groups for OAB symptoms, with no difference between groups. Greater improvement from 12-week single therapy to 24 and 52 weeks of combined therapy was noted in the group originally assigned to intravaginal estradiol. The role of combined medical therapy for OAB symptoms needs further investigation.