Patients are stratified at study entry according to screening CD4 count (below 200 cells/mm3 versus 200 cells/mm3 or higher) and screening HIV-1 RNA copy number (between 1,500 and 10,000 versus 10,000 copies/ml or higher). Then, patients are randomized to receive GM-CSF or GM-CSF placebo subcutaneously 3 times per week for 16 weeks. All patients remain on their current stable potent ART (not provided by this study). During Step 2, all patients receive open-label study treatment, consisting of current potent ART plus GM-CSF subcutaneously 3 times per week for 32 additional weeks. HIV-1 RNA, CD4 counts, and clinical and safety parameters are monitored for all patients periodically until Week 52. Patients who experience an increase in HIV-1 RNA of greater than 1 log 10 from baseline on 2 consecutive determinations or a greater than 50% decrease in CD4 count from baseline (a drop of at least 50 cells) on 2 consecutive determinations at any time during Step 1 or 2 must discontinue all study treatment. Patients who discontinue study treatment for any reason prior to Week 16 continue following the study visit schedule through Week 16.