We performed an extensive two-dimensional differential in-gel electrophoresis proteomic analysis of the cellular changes in human T cells upon human immunodeficiency virus type 1 (HIV-1) infection. We detected 2,000 protein spots, 15% of which were differentially expressed at peak infection. A total of 93 proteins that changed in relative abundance were identified. Of these, 27 were found to be significantly downregulated and 66 were upregulated at peak HIV infection. Early in infection, only a small group of proteins was changed. A clear and consistent program of metabolic rerouting could be seen, in which glycolysis was downregulated and mitochondrial oxidation enhanced. Proteins that participate in apoptotic signaling were also significantly influenced. Apart from these changes, the virus also strongly influenced levels of proteins involved in intracellular transport. These and other results are discussed in light of previous microarray and proteomic studies regarding the impact of HIV-1 infection on cellular mRNA and protein content.