Although effective medications are available for the treatment of acne, tolerance problems may preclude adequate treatment regimens such as topical retinoic acid, and reduce patient compliance. The present study was conducted to evaluate whether a medical water (Avène) in conjunction with retinoic acid may improve local tolerance in acne. A controlled, open, randomised, multicentric study was completed after 28 days of treatment in 69 acne patients, 34 applying a retinoic acid preparation alone, and 35 applying retinoic acid in association with the water spray used ad libitum. Topical retinoic acid treatment induced prominent signs of irritation in both groups. However, a statistically significant reduction between the two treatment groups could be demonstrated on scaling at all assessment visits (p< or =0.02, Wilcoxon test). No significant water effect on erythema, burning and itching was shown during the treatment period. The overall tolerance assessed by the investigator was significantly improved with the water (p = 0.04, Wilcoxon). Taken together, water with a low mineral content appears to be a promising adjunctive treatment for improving the tolerance of topical retinoids in acne.