Case reports suggest that infants with Kawasaki disease have atypical presentations and a high complication rate, likely related to delayed diagnosis and treatment. To date, no study of consecutive cases has compared infants with older children who have both atypical and typical Kawasaki disease. We retrospectively reviewed 44 cases of Kawasaki disease treated at our hospital from March 1980 to 1990: 11 (25%) were infants; 9 (20%) had atypical Kawasaki disease, of which 5 (56%) were infants; the male to female ratio was 1.7:1. Infants had a higher incidence of atypical Kawasaki disease (5 [45%] versus 4 [12%]; P = .007) and of coronary artery complications (7 [64%] versus 3 [9%]; P = .002), and coronary artery complications developed in all of the infants with atypical Kawasaki disease (5 [100%] versus 0 [0%]; P < .01). Yet, the other manifestations and laboratory changes were at least as common as in the older children. Coronary artery complications did not develop in any patient who received early intravenous immune globulin therapy. We suggest that in infants with Kawasaki disease, accepted criteria are too restrictive to allow early diagnosis and effective treatment. Until a definitive test is available, clinical judgment is required in the diagnosis of atypical Kawasaki disease. Intravenous immune globulin is known to be safe, and its early use in patients with suspected atypical Kawasaki disease is appropriate.