Schizophrenic individuals have higher urinary cotinine levels compared to non-schizophrenic individuals with a similar smoking history. This suggests that schizophrenic individuals may absorb higher doses of nicotine. The purpose of this study is to determine whether smokers with schizophrenia or schizoaffective disorder have higher serum nicotine and cotinine levels in comparison to smokers without schizophrenic-related disorders.