The aim of this study was to determine the serum levels of soluble markers reflecting different aspects of immune activation in HIV-1-infected patients, and assess their prognostic significance for occurrence of AIDS-related death before the advent of the highly active antiretroviral treatment (HAART). Serum concentrations of the soluble forms of interleukin-2 receptors (sIL-2R), intercellular adhesion molecule-1 (sICAM-1), and E-selectin (sEs) have been determined in a cohort of 64 HIV-1-infected patients, between 1990-1993. The patients were followed prospectively with regular visits at the outpatient department. Follow-up time was censored at January 1, 1997, the date after which HAART was introduced. The median follow-up time was 46 months (range, 2-78 months). By the end of follow-up, 34 subjects had died. Baseline levels of all three soluble markers were significantly lower in subjects who remained alive during the follow-up compared to subjects who died. Univariate analysis showed that individual sIL-2R and sICAM-1, but not sEs measurements, were significantly associated with time to death (p = 0.008 and 0.003, respectively). Even after adjustment for age and CD4+ T-cell counts sIL-2R measurements remained significantly prognostic. Sensitivity analysis using follow-up time to year 2000 confirmed these results. Our data suggest that assessment of the immune activation status using the easily measured levels of circulating markers may provide additional information about the risk of AIDS-related death. Further studies are needed to assess the effect of HAART on the levels of immune activation markers and their prognostic value.