The relationship between tobacco withdrawal symptoms and pre- and post-cigarette blood nicotine levels, pre-cigarette cotinine levels, change in nicotine level from pre- to post-cigarette, half-life for nicotine, and total smoke exposure was examined in 20 smokers. Subjects' reports of craving for cigarettes were significantly related to blood nicotine/cotinine levels and change in nicotine level from pre- to post-cigarette; questionnaire measures of confusion and number of awakenings during sleep was related to half-life for nicotine; and number of awakenings during sleep was related to behavioral measures of total smoke exposure. These results suggests some symptoms of tobacco withdrawal are related to nicotine deprivation while others are not.