This article updates a 1990 review of the effects of tobacco abstinence by reviewing (a) which symptoms are valid indicators of tobacco abstinence and (b) the time course of tobacco abstinence symptoms. The author searched several databases to locate more than 3,500 citations on tobacco abstinence effects between 1990 and 2004; 120 of these were used in this review. Data collection and interpretation were based solely on the author's subjective judgments. For brevity, the review does not evaluate craving, hunger, performance, and several other possible outcomes as withdrawal symptoms. Anger, anxiety, depression, difficulty concentrating, impatience, insomnia, and restlessness are valid withdrawal symptoms that peak within the first week and last 2-4 weeks. Constipation, cough, dizziness, increased dreaming, and mouth ulcers may be abstinence effects. Drowsiness, fatigue, and several physical symptoms are not abstinence effects. In conclusion, no major changes are suggested for DSM-IV criteria for tobacco/nicotine withdrawal, but some deletions are suggested for ICD-10 criteria. Future studies need to investigate several possible new symptoms of withdrawal and to define more clearly the time course of symptoms.