Objective: The purpose of this article was to perform a reanalysis of the adverse recordings from Phase III studies of Decapinol Mouthwash (containing 2 mg/mL of the active ingredient delmopinol HCl) on patients with gingivitis with respect to occurrence of aphthous stomatitis.Materials and Methods: The adverse events recordings from 8 randomized double-blind clinical studies on patients with gingivitis were statistically evaluated with respect to presence of aphthous stomatitis. The patients were treated for 2-6 months with mouthwashes containing delmopinol HCl 0.2%, delmopinol HCl 0.1%, chlorhexidine digluconate 0.2% or placebo. The number of visits in each study was three. Each time the patients visited the dentist for efficacy determinations, also data like adverse events were recorded. The number of patients with aphthous stomatitis at the different visits was calculated. Meta-analysis using the Fisher's exact test was performed to evaluate how the effect was related to the different treatments.Results: After 4-6 weeks, the patients rinsing with delmopinol HCl 0.2% was the only group showing a significantly better effect than the placebo group.