From the middle eighties, mortality in the age group 15 to 39 years in Andalusia has experienced an important increase; the object of this work is to analyse mortality in this age group, in order to discover the causes which have brought about this increase in mortality and to assess its impact on life expectancy in the eighties. Using the mortality data and the population of Andalusia from 1980 to 1992, specific rates have been calculated, both for mortality by age and cause as well as those adjusted for age. To quantify the impact of the causes of death with respect to life expectancy development, the Pollard method was used. There was a relative increase in the mortality of Andalusian young people between the three-yearly periods 1980-1982 and 1990-1992. The causes contributing to this increase, amongst the male population, were: Aids with an excess of 825 deaths, 575 in traffic accidents, 155 suicides and 147 deaths from drug overdoses. These same causes of death led to total losses of 0.46% years in the gain of life expectancy. Amongst women, on the other hand, the causes of death maintained relatively stable rates, with an almost imperceptible effect on life expectancy at birth. The increase in mortality in the 15-40 age group for causes mentioned previously, is an almost exclusive phenomenon amongst young Andalusian men. This produced a slow-down in any gain in life expectancy during the eighties.