Sinus disease has been assumed to exist in children with respiratory tract allergies. We consecutively evaluated 375 patients (245 male, 130 female) with childhood onset asthma, between 5 and 15 years of age (mean 7.8 years of age). Abnormal Waters radiographs were found in 205 patients (54.7%) which included mucosal wall thickening greater than 6 mm (67.3%), complete opacification (22.9%) and air-fluid levels (9.8%). The level of immunoglobulin (Ig) E was found to be much higher in non-sinusitis asthmatic children than in asthmatic children with sinusitis (1207 IU/mL vs. 644 IU/mL). The IgG, IgA, IgM and erythrocyte sedimentation rate (ESR) values were not significantly different in the two groups. All patients were treated with antibiotics for 3 to 6 weeks. Five patients required surgical intervention after antibiotic treatment had little success. Streptococcus viridans was isolated from 4 patients following surgical aspirates and Peptostreptococcus anaerobius was isolated in only one patient. In conclusion, sinusitis in children may be an aggravating factor for chronic reactive lower airway disease. Optimal treatment may decrease the need of asthmatic medication.