The association conjunctivitis-otitis is highly suggestive of Haemophilus influenzae infection. This conjunctivitis otitis syndrome could be a good model to assess the efficacy of different antibiotic regimen in the treatment of acute otitis media due to HI without tympanocentesis. This prospective randomized trial compared the efficacy of two orally cephalosporins which demonstrate in vitro an activity against HI. This study was conducted from 4.20.1988 to 3.15.1989 and involved 73 children with COS examined in an outpatient clinic. The mean age was 17.7 months. Before treatment culture were taken from the lower palpebral conjunctivae. 81 strains was found: HI 61 (beta-lactamase-producing 15), Streptococcus pneumoniae 16, Branhamella Catarrhalis 4. The 73 patients were treated with 40 to 50 mg/kg/day of the test drug for ten days, 25 with Cefaclor in 3 divided dose (group 1), 24 with Cefatrizine in 3 divided dose (group 2), 24 with Cefatrizine in 2 divided dose (group 3). The recoveries was obtained in 17/25 in the group 1, 18/24 in the group 2, 15/24 in the group 3. There was no significant difference between the 3 groups.