The development of an effective anti-nicotine vaccine to aid smoking cessation, by preventing nicotine from entering the brain, has been hampered by the inability of the tested vaccines to generate consistently high antibody titres in humans. Now, Hicks et al. have created an adeno-associated virus gene transfer vector that is capable of expressing high levels of a monoclonal anti-nicotine antibody. Following systemic nicotine administration, vector-treated mice had markedly lower levels of brain nicotine than did untreated mice, and treatment also prevented nicotine-induced cardiovascular and locomotor effects. Thus, passive anti-nicotine immunotherapy may warrant further study as a possible anti-smoking therapy.