Abstract AIMS: Recent studies suggest that smoking cessation may cause more withdrawal symptoms than thought previously. The widely used Minnesota Withdrawal Scale (MWS-R) was revised recently to include some of these newly described symptoms. We assessed the validity of MWS-R and other proposed self-reported measures of tobacco withdrawal symptoms. DESIGN AND SETTING: An internet survey of daily and former smokers with repeated measurements, followed by a randomized trial among the daily smokers. PARTICIPANTS: Daily smokers (n = 1126) and former smokers (n = 3239). MEASUREMENTS: Participants answered the original MWS (nine items), the eight additional symptoms in the MWS-R and 23 other questions on tobacco withdrawal symptoms. Daily smokers were assigned randomly to either continue to smoke for 2 weeks or to stop smoking, and they answered follow-up surveys 1, 3 and 7 days after their target quit date. FINDINGS: Among the 31 proposed new symptoms tested by comparing recent quitters with continuing smokers, the only withdrawal-like symptom observed was worsening of mood swings. Post-cessation change in mood swings remained statistically significant after adjustment for baseline depression, irritability, impatience, restlessness, stress or anxiety/nervousness. Also, abstinence improved sense of smell, sense of taste and sore throat. Post-cessation change in symptoms intensities did not predict relapse. CONCLUSIONS: Moods swings are a symptom of tobacco withdrawal that can be validly measured and are unpleasant. In contrast, smoking cessation also has positive, immediate effects, including improved sense of smell and taste and reduced sore throat.