Brodimoprim is along acting broad spectrum antibacterial agent. It is a new selective inhibitor of: bacterial dihydrofolate reductase, structurally related to trimethoprim. The aim of the present study was to investigate the efficacy and tolerability of brodimoprim (10 mg/kg on the first day, 5 mg/kg/die onward) in the treatment of upper respiratory tract infections in children (age range: 2-14 years). This open group comparative study was performed either in 68 children affected by bacterial pharyngotonsillitis (37 treated with brodimoprim, 31 with erythromycin 560 mg/kg/8 hours) or in 50 patients affected by otitis media (25 treated with brodimoprim, 25 with amoxicillin/clavulanic acid 50 mg/kg/12 hours) or in 52 patients affected by acute sinusitits (25 treated with brodimoprim, 27 with amoxicillin/clavulanic acid 50 mg/kg/12 hours). All patients were clinically evaluated before admission, during the trial and 48 hours after the last dose of antibiotic. At the same time blood and secretion samples were collected for hematology/biochemistry and microbiological assays. A total of 170 subjects were treated and 141 patients demonstrated a clinical recovery/improvement following the treatment period, with approximately the same recovery rate (83%) among the groups. The bacteriological response was evaluated in 169 subjects. Eradication of pathogens was docu mented in 27 subjects treated with brodimoprim and 28 with erythromycin in the pharyngotonsillitis group, in 22 subjects treated with brodimoprim and 16 with amoxicillin/clavulanic acid in the otitis group and in 17 subjects treated with brodimoprim and 20 with amoxcillin/clavulanic acid in the sinusitis group. The overall eradication in brodimoprim treated patients was 77% in comparison with 76% of eradication obtained in the control groups.