Previous studies have shown that cotinine, a metabolite of nicotine, antagonizes the beneficial effects of the nicotine patch in redugin withdrawal symptoms. Studies have also shown that cotinine enhances serotonin levels. This study examined the effects of several doses of a 5HT3 antagonist, ondanstron, in combination with the nicotine patch. This medication has been observed to reduce nicotine withdrawal symptoms in rats. These effects were compared to the nicotine patch alone. The results of this study produced some modest effects showing that the 8mg dose of ondansetron suppressed tobacco withdrawal symptoms to a greater extent than the nicotine patch alone.