In freely moving intact cats and cats with bilateral lesions of the lateral funicull the foot contact signals and the activity of selected muscles operating at the ankle and knee joints were analysed during walking at moderate speed (0.4-1.0 m/s). No essential changes in the activity of the muscles gastrocnemius lateralis (GL), semitendinosus (ST) and vastus lateralis (VL) were found in operated animals. The tibialis anterior (TA) muscle activity had a shorter duration than the swing phase in operated animals and showed an impaired coactivation with gastrocnemius lateralis (GL) muscle at the end of the swing phase.Pilot experiments indicated that these deficits may be partly compensated for by peroneal nerve electrostimulation. Analysis of regression lines relating the swing duration to the step duration, determined from EMG records, confirmed our previous results, based on foot contact signals (Gorska et al. 1993), showing that in cats with lateral funicular lesions the swing duration varies muchmore with the step duration than in intact animals.