We performed a randomized, double-blind, placebo-controlled study to determine whether acute otitis media could be prevented by antibiotic therapy initiated promptly after the appearance of symptoms of upper respiratory tract infection, One hundred four children aged 1 to 4 years received a 7-day course of either amoxicillin-clavulanate or placebo, Acute otitis media developed in 9 (18%) of the 50 children receiving amoxicillin clavulanate and in 12 (22%) of the 54 children receiving placebo (p = 0.59).