This paper reviews certain clinical and neurochemical aspects of cocaine abuse. Once entrenched patterns of addiction have developed, cocaine addicts suffer progressive financial, medical, psychiatric and psychosocial deterioration that results, to some extent, from cocaine-induced neurochemical alterations in the brain. While cocaine produces euphoria through its stimulatory effect on dopamine neurons, several lines of evidence suggest that dopamine depletion occurs after chronic cocaine abuse. The dopamine neurotransmitter system is therefore a natural starting point for understanding the biology of cocaine addiction and selecting suitable adjunctive pharmacological agents. Furthermore, the dopamine depletion hypothesis implies that cocaine is "physically" addictive and provides a biological framework for understanding this disease and refining present therapeutic approaches.