Comorbid abuse of cocaine and alcohol is a common occurrence. Cocaethylene, the ethyl ester of benzoylecgonine, is an active metabolite formed as a result of simultaneous use of these substances. In humans, the concurrent ingestion of cocaine and alcohol, with resulting cocaethylene formation, has been associated with enhanced subjective euphoria, increased heart rate and increased plasma cocaine concentration. These findings suggest that cocaethylene may play a role in the morbidity and mortality associated with concurrent cocaine/alcohol abuse. This placebo-controlled, double-blinded study examined the behavioral and physiological effects and pharmacokinetics of intranasal cocaethylene administration in humans (n = 8), using cocaine as a comparator. Cocaethylene administration resulted in a euphoria similar to that produced by cocaine, although the effects differed significantly over time. Subjects were unable to distinguish between equimolar doses of cocaine and cocaethylene, although cocaethylene appeared to be eliminated more slowly than cocaine. Cardiovascular effects of cocaethylene and cocaine were similar. These findings are considered in light of the epidemiology and possible consequences of cocaine and alcohol abuse.