Cigarette smoking is highly addictive. Spontaneous quit rates approximate 3%. Even those using nicotine replacement therapy (NRT) have high relapse rates (67-75%) on completion of the 8-12 week course of NRT. Thus there is interest in the use of extended NRT as a "safer" alternative to cigarette smoking. However such assumptions may be premature. Nicotine demonstrates proxidant effects in vitro and in small studies has been associated with endothelial dysfunction. Studies simultaneously assessing the effects of nicotine on oxidative stress and arterial function in humans have not been performed.