Some features of excitatory and inhibitory responses elicited in neurones of area 17 of the Cat by moving stimuli were investigated with both extracellular (69 units) and intracellular (39 units) recordings. Inhibitory responses appeared as gaps in the continuous activity evoked by a conditioning stimulus jiggling in the receptive field (monocular conditioning) in extracellular experiments and as membranary hyperpolarization in intracellular experiments. The hyperpolarization showed features typical for inhibitory postsynaptic potentials and could be reversed to depolarization by injection of negative currentthrough the microelectrode. Response types were classified in several groups according to their excitatory/inhibitory pattern and were generally different in the two opposite directions of motion of the same stimulus. The results are discussed with regard to their implications for intracortical connectivity and receptive field organization.