BACKGROUND: Problem gambling is common across cultures, and has been conceptualized in terms of impulsivity. While elevated rates of attention deficit hyperactivity disorder (ADHD) have been observed in problem gamblers, the relationship between these two conditions, and other dissociable forms of impulsivity, has received little research attention. METHODS: N=126 non-treatment seeking young adults with problem gambling were recruited from the community, and were grouped according to the presence or absence of probable current ADHD. Clinical and cognitive measures pertaining to impulsivity were collected via detailed psychiatric assessment, questionnaires, and computerized neuropsychological tests. These variables were compared between groups. RESULTS: Probable current ADHD was identified in 21.4% of the sample, and was associated with earlier age at onset of gambling behaviors, higher Barratt impulsivity scores (all three subscales), greater caffeine intake, worse response inhibition (Stop-Signal Test), and impaired decision-making (greater proportion of points gambled, Cambridge Gamble Test). Problem gamblers with and without ADHD did not differ on demographic characteristics or the rate of other psychiatric disorders, depression scores, nicotine and alcohol consumption, and body mass index. No significant group differences were found for general response speed, working memory, or executive planning. CONCLUSIONS: ADHD is common in young adults with dysfunctional gambling behaviors and is associated with elevated questionnaire and cognitive based measures of impulsivity, along with heightened caffeine use. Future work should study the causal nature between these factors and the treatment implications of these findings.