Peripheral blood mononuclear cells from HIV-infected subjects have been demonstrated by different methods to die by apoptosis after short time in culture. In the present study the percentages of apoptotic cells have been measured by propidium iodide staining and flow cytometry in PBMC from healthy controls (15) and HIV-infected subjects with asymptomatic (10) or advanced (15) disease, with or without anti-viral treatment. The percentage of apoptosis significantly correlated with clinical stage (CDCII: 15.85% +/- 9.17, CDCIV: 22.6% +/- 5.97, P < 0.001) and the CD4/CD8 CD3 cell ratio. R = -0.57, P = 0.012), while no differences were found in relation to AZT therapy. By adding IL-2 to the cultures the percentages of apoptosis of PBMC from HIV-infected patients were significantly reduced in all experiments.