Cigarette smoking is associated with a higher risk for suicide. The present study was conducted on the hypothesis that suicide smokers show higher nicotine and cotinine levels in blood and urine than non-suicide smokers. We determined nicotine and cotinine levels in blood and urine of 87 deceased individuals (18 suicides and 69 non-suicides) by gas chromatography. The smoking rate was 77.8% for individuals who committed suicide and 42.0% for those who did not commit suicide. Average nicotine and cotinine levels in blood were significantly higher in the suicide smokers than in the non-suicide smokers (nicotine: 93.2+/-46.6 ng/ml versus 25.8+/-14.4 ng/ml, p<0.0001 and cotinine: 378+/-235 ng/ml versus 201+/-137 ng/ml, p<0.005). Average levels of urinary nicotine and cotinine were also significantly higher in the suicide smokers than in the non-suicide smokers (nicotine: 1980+/-2210 ng/ml versus 394+/-376 ng/ml, p<0.005 and cotinine: 1170+/-1330 ng/ml versus 414+/-290 ng/ml, p<0.05). Twenty-six decedents were intoxicated with alcohol, and they included 7 suicides (7 smokers) and 19 non-suicides (15 smokers). Our data suggest that cigarette smokers who commit suicide smoke more heavily than other cigarette smokers.