Child mortality has declined in Sub-Saharan Africa over the last 60 years but the decrease has not been regular: it has accelerated over some periods, as during the last decade, and slowed down in others. This is not solely attributable to HIV/AIDS. This paper examines in detail the trends observed in Senegal, an example of a country with low HIV prevalence but where trends in mortality have resembled those of the whole region. Both national and local level data are used, in particular the data on mortality and causes of deaths produced by the demographic surveillance systems (DSS) in the three rural areas of Bandafassi, Mlomp and Niakhar. Although Senegal experienced an appreciable fall in under-five mortality from the end of World War II, the country experienced a fifteen year stagnation in child mortality in the late 1980s and 1990s. This halt was due to a slowdown in vaccination efforts and a resurgence of malaria mortality linked to the spread of chloroquine resistance. The decrease in malaria and other infectious diseases thanks to renewed vaccination efforts and investment in anti-malaria programmes appears to be the main factor responsible for the return to a very rapid decline in under-five mortality observed during the 2000s.