We estimated the incidence of new HIV infections among non-nationals living in Italy for the period 1992-2004, calculated as the number of new diagnoses among legally and illegally residing non-nationals out of the number of new residence permits (which does not include illegal non-nationals). This incidence was compared to that among Italians by calculating the standardized incidence ratio (SIR) by age and gender. There were 17,309 new diagnoses; 19.0% were among non-nationals. The incidence of new diagnoses among non-nationals was 69 cases per 100,000 residence permits, compared to 8.7 per 100,000 population among Italians. The SIR confirmed the marked difference between the two populations, with the incidence being six times higher among non-nationals, compared to Italians. This difference increased over time: in 1992-1994, it was five times higher among non-nationals, compared to Italians, whereas it was eight times higher in 2002-2004. Although the incidence of infection among non-nationals seems to have decreased in the past 10 years, it is still high if compared to that among Italians, suggesting that non-nationals constitute a population subgroup with a high circulation of HIV. Furthermore, HIV is mainly transmitted through the sexual route among non-nationals, prevalently affecting younger persons and women. Access to testing, treatment, and care needs to be facilitated for non-nationals.