The aim of the present review is to discuss recent acquisitions on the neurophysiological effects of the DA denervation of the striatum, obtained in vitro from single neurone electrophysiological recordings. Nigrostriatal DA system degeneration does not significantly alter the intrinsic properties of striatal cells, but triggers adaptive responses in the striatum, involving glutamatergic neurotransmission. By pairing intracellular recordings from 6-OHDA-denervated striatal projection neurones and the synaptic stimulation of glutamatergic corticostriatal pathway, in vitro experiments contributed to elucidate the intimate alterations that follow striatal DA deafferentation. This experimental approach also allowed to better understand the possible cellular bases of both beneficial and side effects of the pharmacological compounds commonly employed in the treatment of PD.