Mice are useful animal models to study pathogenic mechanisms involved in pulmonary vascular disease. Altered expression and function of voltage-gated K⁺ (Kv) channels in pulmonary artery smooth muscle cells (PASMCs) have been implicated in the development of pulmonary arterial hypertension. Kv currents (I_K(V)) in mouse PASMCs have not been comprehensively characterized. The main focus of this study was to determine the biophysical and pharmacological properties of I_K(V) in freshly-dissociated mouse PASMCs using the patch-clamp technique. Three distinct whole-cell I_K(V) were identified based on the kinetics of activation and inactivation: rapidly-activating and noninactivating currents (in 58% of the cells tested), rapidly-activating and slowly-inactivating currents (23%), and slowly-activating and noninactivating currents (17%). Of the cells that demonstrated the rapidly-activating noninactivating current, 69% showed I_K(V) inhibition with 4-aminopyridine (4-AP), while 31% were unaffected. Whole-cell I_K(V) were very sensitive to TEA, as 1 mM TEA decreased the current amplitude by 32%, while it took 10 mM 4-AP to decrease I_K(V) by a similar amount (37%). Contribution of Ca²⁺-activated K⁺ channels (KCa) to whole-cell I_K(V) was minimal as pharmacological inhibition with charybdotoxin or iberiotoxin, nor perfusion with Ca²⁺-free solution had an effect on the whole-cell I_K(V). Steady-state activation and inactivation curves revealed a window K⁺ current between -40 and -10 mV with a peak at -31.5 mV. Single-channel recordings revealed large, intermediate, and small amplitude currents, with an averaged slope conductance of 119.4±2.7, 79.8±2.8, 46.0±2.2, and 23.6±0.6 pS, respectively. These studies provide detailed electrophysiological and pharmacological profile of the native Kv currents in mouse PASMCs.