Cloninger's neuropsychopharmacological theory identifies heritable temperament traits that are linked to neurotransmitter activity. We tested whether these traits were associated with smoking. The four temperament dimensions of the French-language version of the Temperament and Character Inventory were assessed in three distinct samples recruited on the Internet in 2000-2001. Novelty Seeking (NS) was measured in 775 people, Reward Dependence (RD) in 1,383 people, and Harm Avoidance (HA) and Persistence (P) in 823 people. HA (2.1 points, p.03) and NS (3.2 points, p.01) were lower in never-smokers than in ever-smokers. RD (.6 point, p.01) and P (.5 point, p.01) were lower in former smokers than in current smokers. The level of tobacco dependence was associated with the NS subscore Extravagance (.1 point on the Heaviness of Smoking Index per point on Extravagance, p.01). Motivation to quit smoking was positively associated with the RD subscore Sentimentality (.1 point on a 0-10 scale of motivation per point on Sentimentality, p.01) and negatively with the HA subscore Fear of Uncertainty (.2 point of motivation per point, p.01). Among ex-smokers, age at smoking cessation was negatively associated with P (.5 year per point on P, p.02) and positively associated with the HA subscore Fatigability (.3 year per point, p.04) and with the NS subscore Disorderliness (.3 year per point, p.03). Smoking is associated with heritable temperament traits. Consequences for the treatment and prevention of tobacco dependence are discussed.