Vitamin K prophylaxis prevents hemorrhagic disease of the newborn. The present review estimates the potential magnitude of this problem in less developed countries, assessing the need for prophylaxis, along with its cost-effectiveness and feasibility. Late hemorrhagic disease, occurring between 2 and 12 weeks, often leads to death or permanent disability. Its median incidence in developed countries is 7 per 100,000 births. Incidences in less developed countries may be much higher. Three incidence scenarios are proposed and the corresponding losses of disability-adjusted life-years (DALYs) calculated. Under the intermediate scenario, late hemorrhagic disease accounts for 0.1% to 0.2% of DALYs lost to children less than 5 years of age. Assuming a cost of +1.00 per injection, each DALY saved would cost +133. Decisions on prophylaxis must be made on a national basis, considering mortality levels and causes, health budgets, and feasibility. Comparison with the impact of diseases prevented by breast-feeding shows that concern with hemorrhagic disease should not affect breast-feeding promotion efforts, although strategies for supplementing breast-fed infants must be explored.