Résumé : Objectives - To examine the pattern of survival and factors associated with the outcome of disease in patients with AIDS. Design - Inception cohort. Data collected retrospectively from patients' charts. Setting - 52 clinical centres in 17 European countries. Subjects - 6578 adults diagnosed with AIDS from 1 January 1979 to 31 December 1989. Main outcome measures - Survival after the time of diagnosis. Results - The median survival after diagnosis was 17 months, with an estimated survival at three years of 16% (95% confidence interval 15% to 17%). Patients diagnosed in southern Europe had a shorter survival, particularly immediately after the time of diagnosis, compared with patients diagnosed in central and northern Europe (survival at one year (95% confidence interval) 54% (52% to 56%) 66% (64% to 68%), 65% (63% to 66%), respectively. The three year survival, however, was similar for all regions. The regional differences in survival were less pronounced for patients diagnosed in 1989 compared with earlier years. Improved survival in recent years was observed for patients with a variety of manifestations used to define AIDS but was significant only for patients diagnosed with Pneumocystis carinii pneumonia. The three year survival, however, remains unchanged over time. Conclusions - Survival of AIDS patients seems to vary within Europe, being shorter in southern than central and northern Europe. The magnitude of these differences, however, has declined gradually over time. Short term survival has improved in recent years, but the long term prognosis has remained equally poor, reflecting the fact that the underlying infection with HIV and many of the complicating diseases remains essentially uncontrolled.