Objective: Attention deficit hyperactivity disorder (ADHD); is a common neurodevelopmental disorder with multifactorial etiology. Despite the dominant role of the genetic factors; environmental factors such as diet related features may have effect on ADHD diagnosis and symptomatology. In our study we aimed to compare Mediterranean diet (MD) habits of ADHD group with healthy controls and explore the effect of MD on ADHD symptom severity. Method: All participants were evaluated with semi-structured psychiatric interviews and total of 113 individuals with ADHD and 120 healthy controls were included. Socioeconomic and clinical features of both groups were examined. Adherence to MD was evaluated with Mediterranean Diet Quality Index (KIDMED) and ADHD symptomatology was evaluated with Turgay scale. Results: ADHD group had lower KIDMED scores and worse adherence to MD compared to healthy controls. "Medium adherence" to MD increased the risk of ADHD diagnosis two-folds and "low adherence" to MD increased the risk of ADHD diagnosis five-folds compared to "good adherence". Total KIDMED scores and MD adherence levels were negatively correlated with inattention symptoms. Discussion: Adherence to a healthy diet (MD) seems to be related to lesser inattention problems in addition to lower rates of ADHD diagnosis and this indicates the importance of a "healthy diet" not only in the occurrence of ADHD, but also in the clinical symptomatology. certain dietary habits may play a role in both ADHD development and clinical appearance; but further evaluation is needed to shed light on causality and to determine if dietary manipulation could ameliorate ADHD symptoms.