Breast-feeding is important to infant nutrition, morbidity, and mortality, and to postpartum amenorrhea (hence to birth intervals). Evidence on breast-feeding patterns in low-income countries from nationally representative World Fertility Surveys and secondary sources shows that in all but a few such countries most children are breast-fed for at least a few months. The limited evidence available on trends seems to indicate a decline in the duration of breast-feeding, but in most of Asia and Africa breast-feeding is almost universal during at least the first 6 months. Earlier weaning is common in Latin America.