Cotinine, the major proximate metabolite of nicotine, is present in smokers in higher concentrations and for a longer time than nicotine, yet its effects on information processing have not previously been reported. We studied the cognitive effects of cotinine in non-smokers. Sixteen subjects were tested on three doses of cotinine (0.5, 1.0, and 1.5 mg cotinine base/kg), and placebo, on a choice reaction time (RT) task and on a verbal recall task with short and long lists. Cotinine significantly impaired recall on the long list and displayed non-significant but generally consistent dose-related slowing of RT and N100 latency. The acute effects of cotinine were small, and probably do not account for the cognitive deficits observed in tobacco withdrawal, although the cognitive effects of chronic cotinine administration need to be investigated.