The aim of the present study was to investigate whether hirsutenone affects the human ether-a-go-go related gene (hERG) K(+) channels. Many drugs promote formation of the acquired form of long QT syndrome (LQTS) by blocking the hERG K(+) channels. Hirsutenone, a new candidate for the treatment inflammatory skin lesions, induced a concentration-dependent decrease in hERG K(+) current amplitudes. Hirsutenone significantly decreased the time constants at the onset of inactivation. However, the reductions in the time constants of steady-state inactivation and the recovery from inactivation after hirsutenone treatment were not significant. In addition, the drug had no effect on the voltage-dependent activation curve or the steady-state inactivation curve. In summary, hirsutenone potentially acts as a blocker of hERG K(+) channels functioning by modifying the channel inactivation kinetics.