The cellular responses to vascular injury lead to clinical events such as atherosclerosis, hypertension and restenosis. One common feature of these lesions is the proliferation of vascular smooth muscle cells (VSMCs), that undergo a dedifferentiation process (phenotypic switch). The gold standard treatment of this unwanted vascular remodelling is represented by mTOR inhibitors such as rapamycin and everolimus. However, their numerous side effects had advanced the search for novel, more specific targets. We have previously found that functional expression of Kv1.3 channels contributes to the phenotypic switch of VSMCs, as selective Kv1.3 blockers inhibit VSMCs migration and proliferation. Moreover, proliferation of mouse VSMCs from several vascular beds associates with a Kv1.5 to Kv1.3 channel switch, so that Kv1.3/Kv1.5 ratio can be considered as a landmark of the phenotype. Here, we determined whether this Kv1.5 to Kv1.3 switch is conserved in VSMCs from human vessels, and we investigated the mechanisms involved in this pro-proliferative role of Kv1.3 channels. Human uterine, renal and coronary arteries and saphenous veins were obtained from donors at the Clinic Hospitals of Barcelona and Valladolid, with protocols approved by their respective Human Investigation Ethics Committees. Either freshly dissociated, (contractile) VSMCs or cultured (proliferating) VSMCs obtained from explants were used for expression experiments (to quantify mRNA and protein) and for functional studies (electrophysiology of K+ currents and proliferation experiments). We found that changes in Kv1.3:Kv1.5 mRNA ratio represent an early step during the phenotypic switch of VSMCs. This change is due to the decrease of Kv1.5 expression, as Kv1.3 expression was independent of proliferating stimuli. Functional expression of Kv1.3 and Kv1.5 proteins in contractile and proliferating VSMCs shows a good correlation with mRNA expression data. Selective blockade of Kv1.3 inhibits VSMCs proliferation in all vascular beds. The anti-proliferative effect of PAP-1 (a selective Kv1.3 blocker), was occluded in the presence of ERK1/2 blockers, and PAP-1 treatment decreased PDGF-induced pERK expression in VSMCs. However, PAP-1 effect on proliferation was additive with those of mTOR inhibitors. Altogether, our data indicate that Kv1.3 channels could represent a novel therapeutical target to prevent human VSMCs proliferation. Additionally the specific blockade of Kv1.3 could be used to potentiate the therapeutic effect of the currently used drugs in the treatment of restenosis as they inhibit VSMCs proliferation acting on different mechanisms.