OBJECTIVE To compare the clinical and laboratory features and the rate of echocardiographic coronary artery abnormalities in patients with complete and incomplete forms of Kawasaki disease (KD) and to determine which additional clinical criteria might support a suspicion of KD. METHODS We retrospectively reviewed the medical records of patients with KD who were admitted to the general pediatrics department of the Kremlin Bicêtre Teaching Hospital, France, between January 1995 and May 2006. We compared patients with a fever and four or five of the principal criteria (complete KD) to the other patients (incomplete KD). Clinical and laboratory features were abstracted from the records. RESULTS We identified 63 patients with a mean age of 33 months (+/-31). The male-to-female ratio was 2.47. Four patients were excluded. Of the remaining 59 patients, 39 had complete KD and 20 incomplete KD. The group with complete KD had significantly higher rates of changes in the extremities, conjunctival injection, exanthem, and enanthem; and a significantly lower rate of coronary artery dilation (48.7% vs. 90% in the incomplete KD group, P=0.002). Serum levels of alanine aminotransferase and gamma glutamyl transferase were significantly higher in the complete KD group. No significant differences were found between the two groups regarding age, sex, blood cell counts, or laboratory markers for inflammation. Pyuria was found in 45.4% of patients with complete KD and in 30.8% of those with incomplete KD (P=0.17). Of 14 patients who underwent ophthalmological evaluation, two had uveitis; both of them had complete KD. CONCLUSIONS Incomplete KD shares with complete KD a risk of coronary artery disease. The diagnosis of incomplete KD is challenging but can be supported by the presence of features other than the principal criteria, such as acute anterior uveitis or unexplained pyuria.