Objective: To use familial risk analysis to examine the association between attention-deficit hyperactivity disorder (ADHD) and nicotine dependence (ND). Method: Subjects were children with ( n = 257) and without ( n = 229) ADHD of both sexes ascertained from pediatric and psychiatric referral sources and their first-degree relatives ( N = 1627). Results: ND in probands increased the risk for ND in relatives irrespective of ADHD status. There was no evidence of cosegregation or assortative mating between these disorders. Patterns of familial risk analysis suggest that the association between ADHD and ND is most consistent with the hypothesis of independent transmission of these disorders. Conclusions: These findings may have important implications for the identification of a subgroup of children with ADHD at high risk for ND based on parental history of ND. Examiner la nature de l'association entre le trouble de déficit de l'attention avec hyperactivité et la dépendance à la nicotine: une analyse de risque familial