Nicotine, like the psychostimulants methylphenidate and dextroamphetamine, acts as an indirect dopamine agonist and improves attention and arousal. Adults and adolescents with attention deficit hyperactivity disorder (ADHD) smoke much more frequently than normal individuals or those with other psychiatric conditions, perhaps as a form of self-medication for ADHD symptoms. Nicotine might therefore have some value as a treatment for ADHD. The present study is an acute double-blind crossover administration of nicotine and placebo with smokers (n = 6) and nonsmokers (n = 11) diagnosed with adult ADHD. The drug was delivered via a transdermal patch at a dosage of 7 mg/day for nonsmokers and 21 mg/day for smokers. Results indicate significant clinician-rated global improvement, self-rated vigor and concentration, and improved performance on chronometric measures of attention and timing accuracy. Side effects were minimal. These acute results indicate the need for a longer clinical trial and a comparison with other stimulants in adult ADHD treatment.