The ‘Endangered’ Sakalava Rail Amaurornis olivieri is endemic to wetlands in western Madagascar, where it has been recorded between the Betsiboka river in the north and the Mangoky river in the south. Between August 2003 and November 2006, including dry and wet seasons, we surveyed 36 potentially suitable wetlands throughout its known range. We found Sakalava Rails at five sites: Lacs Kinkony, Ampandra, Amparihy, Sahapy and Mandrozo. At each site the population was small (12–39 individuals) and the highest density was 20 individuals km−2. We found up to 67 birds in each field visit and the total number of birds (sum of maxima at each site) seen was 100. We estimate the total population at the five sites to be 215 rails. We cannot confirm that the population lies within the range estimated in the current Red List (250–999 individuals), although this may yet be proven correct. The typical breeding habitat of Sakalava Rail is lotic marshes with a mixture of large areas of open water, reed Phragmites mauritianus and floating Salvinia hastata. The major threats to Sakalava Rail appear to be habitat loss caused by wetland conversion to rice fields and by fires, disturbance by fishermen and people from local villages, and hunting. Other processes that may alter the ecological character of wetlands and so affect their suitability for Sakalava Rails, such as hydrological change or the effects of exotic fish or vegetation, remain to be investigated.