Cocaine withdrawal in animals causes a transient increase followed by a long-lasting decrease in mesolimbic dopamine transporters, dopamine efflux and the number of dopamine cells firing spontaneously. Other changes in the nucleus accumbens and frontal cortex also suggest alterations in dopamine-receptive neurones and circuits. In humans, brain imaging has provided evidence for some similar, long-lasting changes in dopaminergic neurones and innervated areas. These results suggest a protracted biochemical abstinence syndrome for cocaine. In this review, Michael Kuhar and Nancy Pilotte focus on biochemical changes that occur following withdrawal from repeated cocaine administration. A key question for treatment is whether (some of) these persistent changes underlie withdrawal symptomatology such as anhedonia and relapse.