This paper presents an analysis of the costs of implementing a biodiversity conservation vision for the Niger Delta - Congo Basin Forest Region, a region covering the forests from Nigeria across Cameroon, Equatorial Guinea (EG), Gabon, Central African Republic (CAR), Congo and the Democratic Republic of Congo (DRC), based on an effectively managed and representative protected area network. The Niger Delta - Congo Basin Forest Region has an existing protected area system of about 135,000km^sup 2^. A system of effectively managed protected areas that would maintain a substantial part of the biodiversity would require an additional 76,000km^sup 2^ to be gazetted and an investment for the total system of over $1 billion (10^sup 9^). After this initial 10-year investment an estimated $87 million a year would be sufficient to maintain this system. Overall, current donor expenditure in the present network is probably less than $15 million per year, so over $800 million dollars will have to be found elsewhere. If the international community values the biodiversity of the Niger Delta - Congo Basin Forest Region, it is going to have to cover the cost of maintaining this biodiversity.PUBLICATION ABSTRACT