Limited efficacy, costs, side-effects and complications are issues of concern for most current therapeutic modalities for focal hyperhidrosis. This study evaluated the efficacy of topical oxybutynin 10% gel in treating 61 patients with primary focal hyperhidrosis. The gel was applied to the right or left axilla, palms or soles vs. a placebo compound to the contralateral side for 30 days. A blinded visual grading of the change in starch-iodine tests was performed by 2 non-involved physicians. The Hyperhidrosis Disease Severity Scale (HDSS) and Dermatology Life Quality Index (DLQI) questionnaires were administered before and after treatment. The patients rated their satisfaction with treatment. Fifty-three patients completed the 4-week treatment. Sweat reduction in the drug-treated sweating areas was higher than in the control-treated areas. There was a significant mean improvement in pre- and post-treatment HDSS and DQLI (p = 0.001 for both). Thirty-nine subjects (74%) reported moderate-to-high satisfaction. Twice-daily topical application of oxybutynin 10% gel appears to be an effective, safe and well-tolerated treatment for focal primary hyperhidrosis.