Synaptic inhibition of motoneurons is a critical determinant of the pattern of motor activity during rhythmic movements like locomotion, contributing to such features as the alternating activity patterns in antagonist pairs of muscles.  I will describe studies conducted in my laboratory designed to elucidate mechanisms producing synaptic inhibition in motoneurons and identify the locations of inhibitory synaptic inputs within the dendritic structure of motoneurons.  Synaptic location can be identified by determining motoneuron impedance and changes in impedance produced by synaptic inputs, and this method will be discussed.