Sultamicillin is a mutual prodrug of ampicillin and sulbactam that is chemically linked by a diester bond. This investigational agent has beta-lactamase-inhibiting activity by virtue of sulbactam, a novel beta-lactamase inhibitor. A double blind randomized study was conducted to evaluate the safety, efficacy and tolerance of sultamicillin for treatment of acute otitis media compared with amoxicillin-clavulanate. A total of 144 subjects were included (96 randomly assigned to the sultamicillin and 48 to the amoxicillin-clavulanate groups). No safety concerns for sultamicillin were identified during the study. The clinical efficacy in effusion clearance between the two groups was found not to be statistically different at 10 days (P = 0.23) and 30 days (P = 0.72). Similar rates of side effects, primarily gastrointestinal, were reported in both study groups. Sultamicillin may be an alternative for the treatment of acute otitis media when persistence and recurrence of disease become an issue.