Cameroon contains tropical Africa’s most species-diverse hotspots for plants. This addition to the Red Data Book of the International Union for the Conservation of Nature and Natural Resources documents 815 rare threatened species in Cameroon, most of which have been assessed here for the first time. Since numerous species occur beyond Cameroon, the new assessments are also relevant to Nigeria and Gabon, as far west as Guinea, and as far east as Congo and Rwanda-Burundi. The authors provide short species descriptions to aid identification in the field, notes on habitats and threats, distribution maps, and management suggestions to promote better conservation. This will be an essential publication for the local and international conservation and environmental communities, the international extractive, agricultural, forestry, and development industries, local NGOs, and botanists.