In order to investigate the distribution of Bordetella pertussis in Nagoya City and estimate efficacy of the vaccine, we tried to isolate B. pertussis from patients with Pertussis-like symptoms who went to the department of pediatric general hospitals in Nagoya City from 1989 to 1992. B. pertussis were isolated from 43 patients among 164 patients with Pertussis-like symptoms. All of these isolates were classified into 1, 3, 6 serotype. It was impossible to isolate any B. pertussis in 1992 because of yearly variations. B. pertussis was only isolated from patients who were not vaccinated. Among the 28 siblings of the patients, 18 were vaccinated and 2 fell ill, but the latter had only mild symptoms. Three did not fall ill although they had an incomplete vaccination. According to these results we suggest that this component vaccine is effective.