The objective of this study is to describe the impact of AIDS on the mortality of young adult (aged 25 to 44 years) in Italy, at both the national and regional level. We analyzed the official mortality data for Italy: the most recent data available being from 1990. General mortality trends show that while mortality among young women is still decreasing (i.e. from a standardized rate of 83.8 per 100,000 in 1980 to 68.4 in 1990), mortality among young men began to rise in the mid-1980s, after a steady decrease over many years. Among the 25-34 year olds, however, this reversal in trend is more marked, notwithstanding a decrease or stabilization in most major causes of death. In fact it coincides with the appearance and spread of AIDS in Italy, which has affected young men in particular. (The peak age group for AIDS deaths is the 25-34 year olds). Mortality data from 1990 reveal that AIDS is the fourth leading cause of death in Italy among men between the ages of 25 and 44 years. Among 25-34 year-old men, however, AIDS is the second leading cause of death, after road accidents. AIDS also contributes greatly to the general mortality in individual regions, both among 25-44 year-old men (Lombardy, Liguria, Lazio, Emilia-Romagna, Tuscany), and especially among 25-34 year-old men (Lombardy, Liguria, Lazio, Sardinia, where it is the number one cause of death, Emilia-Romagna, Tuscany, and Veneto, where it is the number two cause of death).