Strategies to limit life-long dependence on antiretroviral therapy (ART) are needed. We randomized 81 human immunodeficiency virus (HIV)-infected subjects to 4 interventional arms involving continued ART plus ALVAC vCP1452 (or placebo) with or without interleukin (IL)-2 infusions. Viral load rebound 12 weeks after ART interruption was then analyzed to assess immune control. Fifty-two subjects reached the study end point. ALVAC recipients had 0.5 log 10 lower virologic rebounds (P = .033). IL-2 plus vaccine boosted CD4 + T cell counts (P < .001) but did not diminish viral rebound. Significant changes were not detected for HIV-specific lymphoproliferative responses in any arm. This exploratory protocol provides useful clinical data for future therapeutic immunization trial design. © 2006 by the Infectious Diseases Society of America. All rights reserved.