It has been shown that Long Term Oxygen Therapy (LTOT) improves polycythemia secondary to hypoxemia and right heart failure, decreases pulmonary hypertension, improves quality of life and increases life expectancy in COPD patients. In our study we aimed to evaluate clinical data, mortality, patient's adherence and efficiency of the therapy in COPD patients receiving LTOT. Mean age was 70.5%±9.7 and 57% of the participiants were male. It was shown that one year hospital admission count after LTOT (0.56±0.79) was decreased according to one year hospital admission count before LTOT (1.14±1.64). When arterial blood gas values after LTOT compared to the values at the time prescription PaO2 was increased (47.9±4, 53.4±9) and PaCO2 was decreased (56.1±11, 50.5±11). Although there was no significant difference in pulmonary artery pressure after LTOT, a significant increase was determined in hematocrit (38.37±6, 40.14±6). 41.1% of the patients had at least once device maintanence, and after LTOT only 38.4% had a clinical control due to COPD. The most common reason for irregular use was lack of necessity. Mean daily oxygen usage was 13.88±4.35 hours/day and 68.8% of the patients were using 15 hours or more. Mean follow-up of the patients were 17.85±14.53 (1-55) months and mortality rate in this period was 67%. Mortality was higher in LTOT with 15hours/day or more compared to less than 15 hours (respectively 54.6%, 12.5%). In conclusion, all patients with an indication for LTOT should be followed by national registry system and monitored in terms of technical services. Patients adherence and routine controls should be provided.