To determine the incidence of cleft lip and/or palate (CL/P) in Aichi prefecture, 485,085 infants born between Jan. 1, 1982, and Dec. 31, 1987, were investigated. 385 infants (0.154%) were found to have these abnormalities; approximately 1.54/1000 live births. Of these infants the number of CL, CLP, and CP was 152 (34.0%), 212 (47.4%), and 83 (18.6%), respectively, (including 1981). These data were compared with those of other prefectures in Japan. The incidence of cleft lip and/or palate in Aichi prefecture was close to the mean for the whole country.