The dry forests constitute one of the most distinct, yet least protected, ecosystems in Madagascar, an island renowned for high levels of endemism. They have generally been considered one of the most intact of Madagascar's climax vegetation types and accordingly have received little conservation effort. In particular, the Mikea Forest, a unique area between the Mangoky and Fiherenana rivers, currently receives negligible formal protection. It contains remarkably diverse plant and reptile assemblages, including several taxa that are found nowhere else, plus the only populations of two threatened bird species: the subdesert mesite Monias benschi and long-tailed ground-roller Uratelornis chimaera. From satellite imagery we estimate that primary forest cover declined by 15.6 per cent from 1962 to 1999, and that the rate of deforestation has increased from 0.35 per cent per annum in 1962–94 to 0.93 per cent per annum over the past 5 years. The most important factors underlying this process are slash-and-burn maize cultivation in the northern Mikea Forest and charcoal production at its southern fringe. Given these alarming circumstances, we suggest that combinations of conservation measures are required to safeguard the biological diversity of the area. Specifically, we recommend the establishment of a large protected area to the north of Manombo, a co-ordinated network of community-based conservation areas throughout the Mikea Forest, development projects to improve agriculture, and a regional research and education centre.