Data from AIDS surveillance systems in the World Health Organization European region (1993-2001) were analysed to describe the main epidemiological aspects of recurrent bacterial pneumonia (RBP) as AIDS-defining illness (ADI) in Europe. Among the 153 756 AIDS cases analysed, 5796 (3.8%) had RBP. The proportion of RBP was higher (8.3%) in eastern than in western Europe (3.6%), possibly because of a greater propensity of certain countries to diagnose RBP. In western Europe, the proportion of RBP as ADI appeared to increase over time up to 1998 (from 2.5% to 4.5%), and declined thereafter (3.3% in 2001). RBP was strongly associated with intravenous drug use (odds ratio 3.0, 95% CI 2.7-3.3), whereas it did not differ in age groups or geographical areas. The study findings confirm the crucial role of intravenous drug use in the occurrence of RBP and suggest that highly active antiretroviral therapies mi.ht have had a postponing impact on the relative frequency of RBP as ADI.