The authors discuss the problem of the diagnosis of sinusitis in children from the viewpoint of the practising paediatrician, on the basis of 106 children and adolescents aged between 6 and 17 years, and suffering from sinusitis. Maxillary sinusitis (56.5%) and a combination of maxillary and ethmoidal sinusitis (24.5%) were commonest, and pan-sinusitis occurred in about 10% of cases. The commonest complaints in the history were cough, headache, pyrexia and rhinitis. The commonest clinical findings were pharyngitis, retropharyngeal drip, tenderness to pressure over the sinus points, otitis media, a deterioration in the general condition, enlarged tender angular lymph nodes, bronchitis and rhinitis. The result of treatment of sinusitis in childhood with the antibiotic used here, doxycycline, are assessed. A successful result was obtained in 94.3% of cases; cure in 77 patients (72.6%) and marked improvement in 23 (21.7%). There were six failures (5.7%). In the majority of children – 72 cases (68%), the duration of treatment was 15–21 days. It was 10–14 days in 18 children (17%) and more than 3 weeks in 16 children (15%). Rapid subjective improvement was seen in 65 cases (61.3%), and rapid objective improvement in 80 (75.5%). The tolerance of doxycycline was very good in nearly all patients. Mild symptoms of gastrointestinal intolerance were seen in two