Postpartum sexual abstinence may be a major determinant of fertility and of maternal and child health in sub-Saharan Africa. This study examines the relationship between ethnicity and abstinence using data from the 1988 Ghana Demographic and Health Survey. There is considerable diversity in the length of abstinence although only for one ethnic group, the Mole-Dagbani and other Ghanaians, is abstinence, both actual and ideal, very long. Respondents in most ethnic groups believe their abstinence to be adequate. A key motivation for abstinence is the unwillingness to have sexual intercourse with nursing mothers. Education, urbanisation, changes in marriage patterns and religious traditions are major factors shaping the ethnic differentials in abstinence. In comparison to breast-feeding, abstinence appears to have relatively little impact on the length of the birth interval and, for Ghana, has relatively few implications for fertility and child health.