To calculate the incidence of recurrent Kawasaki disease and to discuss some potential risk factors for its recurrence, we observed a cohort consisting of those followed-up since the first episode of the disease. A total of 4560 persons, with 16,500.4 person-years were observed from the second month after the first episode of the disease to the end of 1989. The mean observation period was 3.62 years. The overall incidence rate was 5.21 per 1000 person-years, with a higher incidence within the 2 years from the first episode; although not statistically significant, the incidence was higher among males and those who experienced the first episode at < or = 2 years of age. The possibility of i.v. gamma globulin therapy being one of the risk factors was negated by a stratified analysis to control confounding factors but supported by univariate analysis.