We examined the role of the Ca_v1.2 channel for the excitability of hippocampal pyramidal cells by current-clamp recordings in brain slices freshly prepared from wild type mice and mice with the Ca_v1.2 gene inactivated in the forebrain including the hippocampus (Moosmang et al., J Neurosci 2005). As expected, the knock-out had no effect on the shape of single action potentials (AP). Maximal slope of the ascending and the descending phase, half-maximal width as well as threshold and amplitude single AP induced by brief 5 ms current pulse were not significantly different between the two genotypes. In contrast, the threshold for generating a serie of APs by injecting depolarising currents from the resting membrane potential of -70 mV was significantly enhanced in CA1 neurons from mutant mice compared with the control (-42.0 ± 1.0 mV vs. -46.7 ± 1.1 mV; p<0.01). Moreover, the AP frequency within an AP serie was lower in CA1 pyramidal cells from Ca_v1.2 mutants. Our data suggest that the Ca_v1.2 channels are involved in regulating the excitability of CA1 hippocampal neurons. Supported by VW Stiftung, VEGA 2/4009 and APVT51-027404.