Recent studies suggest a possible correlation between Attention Deficit/Hyperactivity Disorder (ADHD) and obesity. In order to explore the topic a systematic review of the literature was performed excluding case reports, non-empirical studies, and studies not using the ADHD diagnostic criteria. Recent studies suggests that obese patients referred to obesity clinics may present themselves with a higher that predicted prevalence od ADHD. Moreover, all studies indicate that subjects with ADHD have higher body weight than expected. However, data on the prevalence of obesity in subjects with ADHD are still limited. Hypotheses about mechanisms underlying the potential correlation between ADHD and obesity suggests that ADHD may contribute to obesity by impulsive eating or disorganised eating habits, impulsivity associated with binge eating might contribute to ADHD symptoms in obese patients, or alternatively ADHD and obesity might be an expression of a common biological dysfunction such as deficit in the reward system. Prospective research, which ic still limited may lead to a better understanding of the correlation between ADHD and obesity as well as the possible mechanisms underlying this comorbidity, contributing to better therapy and thereby improve the quality of life in patient with ADHD and obesity.