Twenty-four atopic children with allergic rhinitis, asthma and maxillary sinusitis were treated with a combination of cefuroxime 50-80 mg/kg/day and N-acetyl-cysteine 15-25 mg/kg/day administered intramuscularly for 10 days. The efficacy of the treatment was judged on the basis of radiological and clinical evolution. The treatment was effective in 95.8% of the children, and 37.5% of them were able to reduce their treatment for asthma. None of the patients suffered severe side effects. The data obtained confirm that appropriate treatment of the sinusitis frequently results in a significant improvement of the asthmatic condition.