Objective: To estimate the prevalence of ADHD in adult patients treated for alcohol dependence and to analyze the characteristics of consumption and psychiatric comorbidity, in function of a possible ADHD in adulthood. Method: We administered the Adult ADHD Self-Report Scale (ASRS) to 726 alcohol-dependent patients. Clinical diagnosis, following Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR) criteria was made in the first four weeks of treatment. A subsample of 297 patients was evaluated using Conners’ Adult ADHD Diagnostic Interview for DSM-IV (CAADID-II) to test the psychometric properties of ASRS. Results: After analyzing the properties of the ASRS (sensitivity: 83.3%; specificity: 66.1%), the prevalence of ADHD, in the whole sample, was estimated to be 16.2%. Being younger, lifetime history of cocaine dependence and the presence of an affective, anxiety or personality disorder were associated with a possible ADHD. Conclusion: The estimated prevalence of ADHD in patients being treated for alcohol dependence is high, and the presence of a possible ADHD in adulthood is associated with an increase in psychiatric comorbidity.