Between June 1, 1979, and May 31, 1984, at The Hospital for Sick Children in Toronto, Kawasaki disease was diagnosed in 163 patients (112 boys, 51 girls, P less than 0.001). Fifteen percent of the children had coronary artery aneurysms. Prior to diagnosis, 24% had been given low doses of aspirin, and 50% acetaminophen. Children with coronary aneurysms had significantly higher temperature during days 10 to 13 of the disease. The febrile phase of the disease was also significantly longer in these children. Coronary artery involvement occurred with equal frequency in boys and girls. There was no significantly greater incidence of coronary artery involvement in infants younger than 1 year of age than in older children. Duration of fever (greater than or equal to 14 days vs less than 14 days) was equally as predictive of the eventual occurrence of coronary aneurysms as the modified Asai score.