Objectives: Estimate the rate of anxiety disorders (AD) and associated factors among patients with substance use disorder (SUD) in Lebanon. Methods: A cross-sectional study, conducted between April and September 2017, enrolled 57 inpatients with SUD. Results: The rate of AD in patients with SUD was 61.4%. The university level of education compared to the primary level of education (ORa = 0.221) was significantly associated with lower anxiety among patients with SUD. Being sexually abused and having a family history of depression tended to significance. Practical Implications: AD is widespread in Lebanon and high rates of anxiety in patients with SUD were found, warranting the implementation of strategic interventions and establishing national policies and legislation for mental health services to provide optimal care. K E Y W O R D S addiction, anxiety disorder, risk factors, substance use disorder 1 | INTRODUCTION Anxiety disorders (AD) are among the most commonly occurring mental disorders worldwide, estimated to have a lifetime prevalence up to 33% 1 and a global prevalence ranging from 4.8 to 10.9%. 2 In Lebanon, 11.2% of the people suffer from an anxiety disorder, which represents around 560 000 inhabitants out of a total of about 5 million. 3,4 Lebanon witnessed a series of wars, local armed combats, and terrorist attacks, 5 in addition to a series of crises including clean water penury, electrical power failure, and waste management problems that had overwhelmed the country. 5 Moreover, a high number of Syrian refugees had led to high levels of unemployment and competition for employment with locals. This is concurrent with the lack of public awareness about these Souheil Hallit and Fouad Tahan are last co-authors. This work has been done in the frame of the "Behavioral and Cognitive Neuroscience Master 2 Program," Faculty of Sciences, Lebanese University.