A random sample of 23 591 single livebirths was drawn from the Singapore Registry for 1967-1974, and information extracted from the birth certificates. The proportion of low birthweight infants (2500 g or less) fell markedly from 9.1% in 1967 to 5.7% in 1974, which has not been the finding in other studies. Variation in the proportions of low birthweight infants by sex, maternal age, parity, and social class, are broadly in agreement with other studies. Indians were found to have significantly smaller babies (mean weight of 3020 g) with a higher proportion of low birthweight ones (11.5%) than the Malays (3080 g and 8.1%) and the Chinese (3130 g and 6.1%). This is despite similar distributions of gestational age, and for term babies the differences in low birthweight proportions are highly significant with Chinese 5.0%, Malays 6.5%, and Indians 9.8%. The reasons for this are discussed with the implication that lower birthweights in Indians are to some extent of ethnic/genetic origin.