Voltage-activated K⁺ currents resistant to TEA but blockable by 4-AP were recorded from mouse pancreatic islet cells. These currents first become observable during depolarizations to voltages more positive than –40 mV, reaching a peak amplitude of 120±34 pA at +6 mV (n=4), display rapid turn on (=3.3±1.1 ms at +6 mV) and inactivate completely within 250 ms (=65±5 at +6 mV). The current is subject to steady-state inactivation. The midpoint (V _h) of the inactivation curve (h) was observed at –72±2 mV. The properties of this current resemble those reported for the A-current in neurons.