Using a unique set of birth registration data from the Demographic Surveillance System of the International Centre for Diarrhoeal Disease Research, Bangladesh, for the period 1974–77, and socioeconomic information collected in the 1974 census, fertility was studied in relation to occupation, size of dwelling, number of cows and number of boats owned. The total fertility rate was found to vary between 6 and 6·5 except in the famine year of 1975. There was no consistent relationship between fertility and education of women. Fertility differentials by occupation showed that the household heads who were farm labourers had relatively lower fertility compared to other occupational groups, except for the year 1977 where the families of service holders were found to have relatively lower fertility. There was a consistent direct relationship between the dwelling size and fertility for each of the years.