Retrospective study was carried out in 1,15,851 consecutive births in five hospitals, and prospective study of 10,415 consecutive births in one hospital of West Bengal. The overall frequency of congenital defects was 4.42/1000 live births. Incidence of NTD and talipes was predominant in rainy season, whereas cleft palate with/without hare lip had highest frequency during winter. Incidence of these anomalies decreased with increasing birth order. The frequency was noted to decline with increasing maternal age, 21-25 years age group had maximum number of malformed babies. Sex ratio and religion, however, did not have any correlation with the incidence of these malformations. When comparison was done between urban and rural population no statistically significant variation was observed. © 1989 Dr. K C Chaudhuri Foundation.