T-type calcium channels (Ca_V3 channel family) are involved in defining of the resting membrane potential and neuronal activities such as oscillations and rebound depolarisation. Their physiological roles depend upon the channel activation and inactivation kinetics. A fast inactivation that stops the ionic flux of calcium in tens of milliseconds has already been described in both native and heterologously-expressed channels. Here, using HEK293 cells expressing the rat Ca_V3.1 channel and whole-cell voltage-clamp, we investigate an additional inactivation process, which can be distinguished from fast inactivation previously described by its slow time course of recovery from inactivation (tau = 1 s) and by its sensitivity to external calcium. Steady-state slow inactivation is voltage dependent around resting membrane (V_0.5 = -70 mV, slope factor = 7.4 mV) and can reduce the calcium current by up to 50 %. Near resting potential, the slow inactivation displays a half- time of induction of tens of seconds. The slow inactivation therefore modulates the availability of T- type calcium channels depending upon recent cell history, providing a mechanism to store information in a time-scale of seconds.