HIV-infected individuals are frequently active, but guidelines for exercise in this population lack scientific support, since studies on the effects of exercise training on immunologic variables of HIV-1 positive individuals have shown conflicting results. Exercise capacity, immunologic markers (CD4, CD8 and CD4:CD8 ratio), anthropometric measurements, and depression scores were evaluated to compare the effects of two intensities of aerobic exercise on HIV-1 seropositive individuals. Twenty-one healthy subjects (14 men, 7 women), carriers of the HIV-1 virus (CD4>200 cells x mm(-3)), and inactive for at least 6 months, completed a 12 week exercise training program (36 sessions of 1 h, 3 times per week), in a moderate intensity group (60+/-4% of maximal heart rate) or a high intensity group (84+/-4% of maximal heart rate). Exercise capacity estimated by treadmill time was increased significantly in both moderate intensity (680+/-81 s before; 750+/-151 s after) and high intensity (651+/-122 s before; 841+/-158 s after) groups, but the high intensity group presented a significantly larger increment (p<0.01). There were no significant changes in the immunologic variables, anthropometric measurements or depression scores. Thus, HIV-seropositive individuals that participate in moderate and high intensity exercise programs are able to increase their functional capacity without any detectable changes in immunologic variables, anthropometric measurements or depression scores.