HIV infection is characterized by persistent immune activation, increased production of proinflammatory cytokines, and rapid T cell turnover. The autonomic nervous system exerts a regulatory effect on the inflammatory response mediated by acetylcholine. We investigated whether an acetylcholine esterase inhibitor would diminish the T cell overactive phenotype characteristic of chronically infected HIV patients. We carried out a proof-of-concept, placebo-controlled study involving 19 subjects chronically infected with HIV-1. Nine patient received pyridostigmine and 10 took a placebo. T cell activation measured by expression of CD69 (p = 0.025) diminished in those taking pyridostigmine. The drug also diminished in vitro T cell proliferation induced by PMA and ionomycin (p = 0.026). IFN-gamma release was diminished in the pyridostigmine group (p = 0.016) and expression of IL-4 (p = 0.010) and IL-10 (p = 0.015) increased. Here we showed that pyridostigmine is able to modify T cell overactivation and proliferation in patients chronically infected with HIV. Pyridostigmine led to an increase in the antiinflammatory cytokine IL-10 and a decrease in T cell proliferation and production of the proinflammatory cytokine IFN-gamma.