We reviewed the chest x-ray (CXR) findings and clinical courses of 129 patients with Kawasaki disease and found abnormal CXR findings in 14.7% of the patients. Reticulogranular pattern was the most frequent abnormality (89.5%), while peribronchial cuffing (21.1%), pleural effusion (15.8%), atelectasis (10.5%) and air trapping (5.3%) were also seen. In each of these patients, CXR abnormalities appeared within 10 days after the onset of illness. In the group with abnormal CXR findings, a statistically significant increase was noted in duration of fever, incidence of adventitious sounds, serum CRP levels and incidence of coronary arterial lesions and pericardial effusion, as compared with the group having normal CXR findings. The pathological basis of these CXR changes is not clear, since no biopsy or autopsy specimen was obtained from these patients, none of these patients showed definite heart failure, it is difficult to consider that abnormal CXR findings were due to heart failure. On the other hand, physical signs and previous pathological reports suggested that the causes of abnormal CXR findings were lower respiratory tract inflammation and/or pulmonary arteritis.