Despite medical advances and improvements in health and social security systems, responsible for increasing life expectancy, social and spatial inequalities in mortality are intensifying in Western countries. This article analyse the evolution of social differences in mortality in Belgium over the last 25 years and their spatial transposition at the districts level. It is based on the matching of National Register data with those of the 1991, 2001 and 2011 population censuses, whereby social and district-based mortality tables were produced. Social groups are formed from a multidimensional indicator combining the level of education, socio-professional category and housing characteristics.The results highlight the existence in Belgium of significant social inequalities with regard to death, which have increased since the beginning of the 1990s. These mortality differences and their increase concern men as well as women and all ages, but especially people aged 25 to 50 years old. As part of the health transition, the disadvantaged social group is significantly behind other social groups, with a smaller contribution of people over 65 to improving life expectancy at birth.These trends are found at the regional and districts level. Moreover, within the same social group, significant mortality differences remain between Flanders and Wallonia as well as between the types of districts. This shows that, while spatial variations in mortality largely depend on the socioeconomic characteristics of their population, elements related to the physical, social and institutional environment of populations also contribute to it.