The Wnt/beta-catenin pathway is involved in cell functions governing development and disease. In modeling post-entry restriction to HIV replication in astrocytes, we reported that part of this natural resistance to productive replication of HIV in astrocytes involved expression of proteins of the Wnt/beta-catenin signaling pathway. We determined here whether induction of beta-catenin signaling in peripheral blood mononuclear cells (PBMCs) can modulate HIV replication. Given that lithium is an inducer of beta-catenin signaling, we used it as a tool to determine the impact of beta-catenin signaling on HIV replication in PBMCs. We demonstrate that lithium inhibited the replication of T-tropic and primary isolates of HIV by >90% and does so in noncytotoxic/noncytostatic concentrations and in a beta-catenin-dependent manner. Specifically, inhibiting beta-catenin signaling by transfection of dominant negative mutant constructs to either T cell factor 4 (TCF-4), the down-stream effector of Wnt signaling, or beta-catenin, the central mediator of this pathway, abrogated the ability of lithium to inhibit HIV replication. Moreover, when Wnt/beta-catenin signaling was inhibited, the level of HIV replication was enhanced by four-fold. To confirm the in vivo relevance of the beta-catenin pathway in repressing HIV replication, we evaluated HIV-positive antiretroviral (ART)-naܯve patients who were on lithium therapy. These patients demonstrated reduction in viral load, which increased as the dose of lithium was reduced. Collectively, these data indicate that beta-catenin signaling is an intrinsic molecular pathway restricting HIV replication in PBMCs.