Objective: To assess pre-AIDS mortality in HIV-infected patients in England, Wales and Northern Ireland during the period 1982-1996. Design: Surveillance data on pre-AIDS and AIDS deaths reported to the PHLS-AIDS Centre were analysed. Methods: Pre-AIDS mortality was estimated as the proportion of pre-AIDS deaths among all deaths in HIV-infected people. Trends over time in the number of pre-AIDS and AIDS deaths were compared using Poisson regression with logarithmic link. Causes of pre-AIDS deaths were recorded. Comparisons were made between the pre-AIDS and the AIDS death groups by logistic regression for: age, location of residence at death, year of death and risk exposure. Results: Four-hundred and sixty-eight pre-AIDS deaths and 8574 AIDS deaths were identified. Pre-AIDS mortality accounted for 5.0% of HIV-related deaths. Trends over time in the number of pre-AIDS and AIDS deaths were not significantly different (P = 0.11). Reported causes of pre-AIDS death included pneumonia (92), liver disease (62), septicaemia (51), malignancies (49), suicide (45), cardiopulmonary causes (46), haemorrhage (42), overdose (24) and accidental causes (24). Factors positively associated with pre-AIDS death were injecting drug use, haemophilia and blood transfusion, residence outside the Thames regions, and death at an older age. Conclusions: Pre-AIDS mortality represents a substantial proportion of HIV mortality, particularly where injecting drug use is a frequent route of HIV transmission.