The IUCN SSC organized two regional workshops, one for West and Central Africa (2005) and one for Eastern and Southern Africa (2006), to produce regional conservation strategies for the lion. Tanzania authorities, together with local stakeholders, took part in the regional exercise for establishing the Regional Conservation Strategy for the Lion in Eastern and Southern Africa, and soon after organized the first national workshop to prepare a National Action Plan for lion and leopard. In 2009, the Tanzania authorities expressed the will to update the lion profile in the country and to hold the second national workshop for finalizing a Lion National Action Plan. The present survey has attempted to update the conservation status of the lion in Tanzania. The final report of this survey is expected to bring comprehensive material for submission to the forthcoming National Action Plan workshop. The methods used are explained and results are provided and discussed. A georeferenced database has been set up to collect and analyse the information available (250 bibliographic references) as well as the information generated by specific inquiries (among 321 informants). Nine thematic maps have been drawn. The lion range in Tanzania is still extensive with a surface of 750,000 km2, i.e. 92% of the terrestrial surface of the country, of which 335,000 km2 (i.e. 45%) are located inside Protected Areas (National Parks and Hunting Areas). An assessment of the lion population size has been attempted with a tentative figure of about 16,800 individuals in Tanzania at this stage, a large majority of them living in Protected Areas (i.e. 80%). Tanzania hosts the largest lion population in Africa and is the first country in terms of lion trophy hunting with around 200 free-ranging lions legally harvested per year. This figure remains far smaller than the number of lions illegally killed for various reasons such as ritual killing, snaring for bushmeat, retaliation in reaction to human casual