We examined the prevalence of abnormalities found by sinus x-rays in patients with asthma. The overall prevalence of abnormalities found was greater in the patients with asthma, 43 of 138 (31.2%), compared to control patients with dental problems, 0 of 50 (p less than 0.001). However, the percent of patients with abnormalities found by sinus x-rays was the same whether the asthma was mild, requiring minimal medication, or severe, requiring multiple medications. The results provide no support for the hypothesis that sinusitis, as detected by abnormalities found by sinus x-rays, aggravates asthma and promotes increased need for medication to control the asthma.