Objective: Opioid addiction is a chronic, relapsing and psychosocial disorder. In opioid addiction patients, studies show that sleep disorders, deteriorated quality of sleep and sleep architecture changes might be seen. In addition, comorbid psychiatric disorder and depression are frequently seen in opioid addicts. Comorbid psychiatric disorders and symptoms worsen of sleep quality in opioid addicts. This study aims to evaluate the quality of sleep during the periods of pre-treatment and in early opioid agonist maintenance treatment in the opioid addicts. Methods: The research included 29 patients in the Alcohol and Substance Addiction Treatment Unit of Trakya University Faculty of Medicine who have met diagnostic criteria for opioid addiction according to DSM-5, completed 28-day treatment, and admitted for control to Alcohol and Substance Addiction Treatment Unit after 1 month from discharge. The Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale, Pittsburgh Sleep Quality Index are administered to all the patients who participated to the study on the day 1, day 28, and in the month 2. All the patients were treated with buprenorphine and naloxone combination. Results: In our study, a time-dependent significant de-crease from day 1 to month 2 was determined in the average scores of the Pittsburgh Sleep Quality Index, which evaluates the sleep quality. In addition, the Pittsburgh Sleep Quality Index average scores showed differences in all time periods. Our study also determined a time-dependent significant decrease in the average scores of the Hamilton Depression Rating Scale and the Hamilton Anxiety Rating Scale, which evaluates respectively the depressive symptoms and anxiety symptoms on the day 0, day 28 and day 60. Discussion: In our research, we evaluated the sleep quality and the symptoms of depression and anxiety of the patients diagnosed with opioid addiction in pre-treatment and early period of opioid agonist maintenance treatment, and showed that those symptoms were getting better with treatment. We think that these findings can guide further research, as they show that opioid treat-ment does not only serve for addiction treatment but also for the treatment of the symptoms accompanying the opioid addiction. [Anadolu Psikiyatri Derg 2018; 19(5.000): 466-471]