Each year, an estimated half million women die from complications related to child birth either during pregnancy, delivery or within 42 days afterwards. When pregnant women have complications, their infants are at greater risk of becoming ill, permanently disabled or dying. For every maternal death, there are at least 20 infant deaths: stillbirths, neonatal or postneonatal deaths. Altogether, an estimated 7 million infants each year die perinatally (stillborn or deaths within the first week of life). Low cost, feasible, and effective intervention strategies include: a) improved family planning and abortion services; b) obstetric care at delivery; and, c) prenatal services. Two hypothetical populations of one million (a low mortality and a high mortality country) are used to illustrate maternal and perinatal program strategies and priorities. In countries with high fertility, major reductions in maternal and infant deaths result both from reductions in the number of pregnancies through family planning and from improved obstetric care. Where fertility is already low, reductions result almost entirely from improved obstetric and prenatal care. The investments required are relatively low, while the potential gains are great. The cost to avert each death in a high mortality population is estimated between $800 and $1,500 or as low as $0.50 per capita per year. The priorities for programs targeting maternal and perinatal health depend on demographic, ecologic and economic factors, and should include the promotion of good health, not merely the avoidance of death. More operational research is required on various aspects of maternal and perinatal health; in particular, on the cost-effectiveness of different service components.