An open study comparing cefadroxil and cephalexin was conducted in children with bacterial infections of the respiratory tract. Patients received 50 mg/kg/day cefadroxil in two equally divided doses twice daily or 50 or 100 mg/kg/day cephalexin in four equally divided doses four times daily. Both drugs were given as suspension. Duration of treatment was generally 9–10 days. A complete cure, defined as relief of the clinical symptoms of infection as well as eradication of pathogens, was achieved in 37 (93%) of the 40 patients treated with cefadroxil, 15 (75%) of the 20 given 50 mg/kg/day cephalexin, and all 20 who received 100 mg/kg/day cephalexin. No signs of relapse or reinfection were noted in any patient during the 2- to 30-day follow-up period. Side effects with both drugs were minor and infrequent. Cefadroxil at a dose of 50 mg/kg administered on a twice-daily basis appears to be equivalent in terms of clinical efficacy to 100 mg/kg cephalexin given four times daily.