The Uluguru Mountains in eastern Tanzania contain at least 16 endemic vertebrate and 135 endemic plant taxa, with hundreds of more taxa shared only with forests in eastern Tanzania and Kenya. This degree of endemism is exceptional in tropical Africa, and the Uluguru Mountains are one of the 10 most important tropical forest sites for conservation on the continent. Surveys carried out during 1999–2001 updated information on the status of forests and biodiversity across the Uluguru Mountains. Forest area has declined from c. 300 km2 in 1955 to 230 km2 in 2001. Forest loss has been greatest over altitudes of 600–1,600 m, and concentrated in submontane forest. During the recent surveys most of the endemic and near-endemic vertebrate species known from the Uluguru Mountains were re-recorded, but three endemic snake species and two near-endemic bird species were not found. These species were previously known from the elevations where deforestation has been greatest. More than 50 plant species are also known only from the altitude range that has been heavily deforested. The primary cause of forest loss has been clearance for new farmland. The forest that does remain is largely confined to Catchment Forest Reserves managed for water by the Tanzanian Government. Without these reserves the loss of forest, and hence the loss of biodiversity, in the Uluguru Mountains would most likely have been much greater.