During walking, maintenance and coordination of activity in leg motoneurons requires intersegmental signal transfer. In a semi-intact preparation of the stick insect we studied membrane potential modulations in mesothoracic (middle leg) motoneurons and local premotor non-spiking interneurons that were induced by stepping of a front leg on a treadmill. The activity in motoneurons ipsilateral and contralateral to the stepping front leg was recorded from neuropilar processes. Motoneurons usually exhibited a tonic depolarization of up to 5 mV throughout stepping sequences. This tonic depolarization depended on membrane potential and was found to reverse in the range of -32 to -47 mV. It was accompanied by a mean membrane resistance decrease of about 12 %. During front leg stepping, an increased spike activity to depolarizing current pulses was observed in 73 % of contralateral flexor motoneurons that were tested. Motoneurons ipsilateral to the walking front leg exhibited phasic membrane potential modulations coupled to steps in accordance with previously published results (Ludwar et al. 2005). Coupling patterns were typical for a given motoneuron pool. Local non-spiking mesothoracic interneurons that provide synaptic drive to tibial motoneurons, also contribute to the modulation of membrane potential of tibial motoneurons during front leg walking. We hypothesize that the tonic depolarization of motoneurons during walking is a cellular correlate of arousal that usually increases effectiveness of phasic excitation in supporting motoneuron firing.