It has consistently been reported that older AIDS patients have a shortened survival compared with younger patients. The aim of the present study was to investigate whether this difference in survival is caused by differences in the pattern of the complicating diseases. Information on patient follow-up after the AIDS diagnosis was obtained by retrospective case note review. The 6,546 patients were followed from the time of AIDS diagnosis as part of the multicentre AIDS in Europe study, which examined AIDS cases diagnosed at 52 centres in 17 European countries between 1979 and 1989. Occurrence of AIDS-defining events and demographic variables were recorded for all patients, and CD4 lymphocyte count at the time of AIDS diagnosis for approximately half the patients. After adjusting for imbalances in other variables, persons ≥50 years of age had a significantly higher risk of contracting AIDS wasting syndrome, AIDS dementia complex and oesophageal candidiasis after the initial AIDS diagnosis, compared with age group 30–39 years [relative risk (RR) 95% confidence interval (CI)], 3.23 (2.70–3.75 CI); 2.48 (2.16–2.80 CI); 1.55 (1.26–1.83 CI), respectively]. Shortened survival after the time of AIDS diagnosis was associated with older age. After adjusting for pattern of complicating diseases, the age effect remained unchanged. Older age predisposes to AIDS-related wasting syndrome, AIDS dementia complex and oesophageal candidiasis. Independent of these differences, older age is significantly associated with shortened survival, suggesting that factors such as severity of complicating diseases or the capability of handling serious infections, rather than disease pattern, are responsible for the shortened survival.