Traditional medicine, including the knowledge, skills and practices of holistic health care, exists in all cultures. It is based on indigenous theories, beliefs and experiences and is widely accepted for its role in health maintenance and the treatment of disease.Medicinal plants are the main ingredients of local medicines, but rapid urbanization is leading to the loss of many important plants and knowledge of their use. To help preserve this knowledge and recognize the importance of medicinal plants to health care systems, the WHO Regional Office for the Western Pacific has published a series of books on Medicinal Plants in China, the Republic of Korea, Viet Nam and the South Pacific. Medicinal Plants in Papua New Guinea is the fifth in this series. This book covers only a small proportion of the immense knowledge on traditional medicine, the plant species from which they are derived, the diseases they can treat and the parts of the plants to be used. The diverse cultures, languages and traditional practices of Papua New Guinea made this a particularly challenging project. But we believe the information and accompanying references can provide useful information for scientists, doctors and other users.