In order to find suitable markers for selection and monitoring of antiviral therapy in asymptomatic HIV-infected patients, we evaluated 18 anti-HIV positive individuals at three monthly intervals by HIV culture, HIV antigen, and core (p24) antibody testing as well as by measurement of lymphocyte subsets. Consistent results were obtained with HIV antigen, p24 antibody testing and T4 cell enumeration, whereas results of virus detection were variable. Therefore cumbersome and expensive virus culture is not of use in selecting patients for antiviral therapy. On the basis of our results and recent literature we currently propose using absence of p24 antibodies, presence of HIV antigen and low or falling T4 cells as eligibility criteria for antiviral therapy in asymptomatic infected individuals.