Introduction: It has been postulated that adult ADHD often goes untreated and undiagnosed. Distinguishing it from other comorbid psychiatric conditions that are more common in the clinical adult population is a challenge. Adult ADHD is reported to coexist with Bipolar Disorder (BD), yet this has been insufficiently studied. It has also been suggested that affective temperaments can explain the affective disturbances in ADHD patients. This study aims at assessing the comorbidity of ADHD with other mental disorders in a Lebanese clinical population, with a special focus on ADHD’s association with BD and temperament. Methods: Data was collected on 1,305 new patients presenting for a consultation at MIND Clinics between January 2014 and December 2016. ADHD/Attention Deficit Disorder (ADD) status was based on a clinical diagnosis, not always following strict DSM-V criteriPatients were grouped into definite, probable and possible past or current ADHD or ADD. The Hypomania Checklist-32 (HCL-32) and the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-autoquestionnaire version (Temps-A) were self-filled by the patients. Results: Patients with ADHD had higher rates of BD, and Substance Use Disorder (SUD) compared to non-ADHD patients, with 57.6% versus 33.6% and 28.4% versus 13.8%, respectively.. Adjusting for age and gender, patients with BD and SUD were 2.3 (95% CI=1.5, 3.6) and 1.8 (95% CI=1.1, 2.8) times more likely to have ADHD respectively. Nonetheless, having psychotic symptoms was protective (OR=0.6, 95%CI=0.3, 1.0). Patients with ADHD had significantly higher HCL-32 and Cyclothymic and Irritable temperament scores than non-ADHD patients in the total, BD and non-BD samples (all p-values <0.05). The same analysis is currently being repeated on a large sample. Discussion and Conclusions: Having ADHD is highly associated with having BD and SUD, , echoing findings from developed countries. Moreover, patients with ADHD having higher scores of cyclothymic and irritable temperaments might be reflective of the fact that these two temperaments characterize ADHD and could be used to fine tune clinical ADHD diagnosis. Future studies with larger samples and longitudinal design are needed to confirm these findings.