Amongst the wide variety of potassium channels, ATP-sensitive K⁺ (K_ATP) channels exhibit the unique feature to couple the cell metabolism to the cellular excitability by regulating transmembrane K⁺ fluxes. The molecular structure of K_ATP channels is now well characterized, their presence has been described in several tissues and their function has been intensively studied. However, such channels remain poorly characterized in the reproductive system. The aim of the present study was to investigate the putative existence of K_ATP channel subunits and their functional role in human syncytiotrophoblast. Immunodetection of K_ATP channel subunits by ABC-DAB and immunofluorescent techniques revealed both the Kir6.2 and SUR2 subunits in the syncytiotrophoblast of human term placenta. The presence in human term placenta of those two subunits, Kir6.2 and SUR2, was further confirmed by immunoblotting and RT-PCR. The potential involvement of K_ATP channels in human placental lactogen (hPL) and human chorionic gonadotrophin (hCG) release was evaluated by incubating human term placental explants in the presence of increasing concentrations of known modulators of K_ATP channels. The hCG and hPL secretory rates were unaffected by the addition of glibenclamide or tolbutamide, two hypoglycaemic sulfonylureas, or the presence in the incubation medium of K_ATP channel openers such as diazoxide and pinacidil. Our study documents the presence of K_ATP channel subunits, Kir6.2 and SUR2, in the human syncytiotrophoblast suggesting that such a tissue might be equipped with functional K_ATP channels. However, the activation or inhibition of these putative K_ATP channels by different pharmacological tools did not affect the hPL and hCG secretory rates from incubated placental explants.