This policy-relevant study grew out of an evaluation conducted by its authors - all scholars at the London School of Hygiene & Tropical Medicine and the Royal Tropical Institute, Amsterdam - of the World Health Organization's Action Programme on Essential Drugs. Their review, involving 13 country studies and WHO's five regional offices, looks at how the idea of a rational drug policy in developing countries came about, evaluates the achievements in specific countries, and discusses some of the issues that remain to be resolved - particularly issues around AIDs, contraception and cost recovery. It should prove useful to policy makers and academics, teachers and students, managers and professionals, as well as international agencies in the health field.