The research focuses on the health sector of Lesotho in the second half of the 20th century by examining four Catholic mission hospitals run by the Catholic church of Lesotho, administrated by different orders of Franco-Canadian and Basotho nuns, and staffed by Swiss doctors recruited by the former “Schweizerischer Katholischer Missionsärztlicher Verein”. It is situated temporally between the 1950s and the 1990s. The aim of the study is to examine how decolonization, changing discourses on development and the nature of mission, and old and new medical challenges such as Tuberculosis or HIV transformed the hospitals as places of healing, as well as how they influenced the doctors, nurses, administrators, and patients. The relevance and aim of the research lie in the generation of historical knowledge on several topics: firstly, new insights into the health system of Lesotho throughout and after decolonization will be generated, thereby showing how the health system changed and coped with the end of colonial rule, lack of financing, and structural adjustment programs in the years after independence. Secondly, the study will generate insights into the history of Christian mission, especially after decolonization, and specifically on the role that mission played in building and maintaining a post-colonial health system. Here, questions of power relations will also play a role. Thirdly, historical knowledge on the impact of different disease will be generated, especially on the reaction of the Basotho health system to the emergence of HIV.