Objective: Erros in prescribing, making or using orthoses frequently used in rehabilitation practices may cause important problems. In this study, we aimed to investigate the factors that cause patients with stroke, spinal cord injury (SCI) or cerebral palsy (CP) to misuse or discontinue their lower extremity orthoses. Material and Methods: The study included 111 patients (59 females, 52 males) who were hospitalized in Kırıkkale Universty Faculty of Medicine PMR Clinic and between Jan 2017-July 2018 and were prescribed lower extremity orthosis, with the diagnosis of stroke (43-38,7%), SCI (22-19,8%), CP (46-41,8%). Factors that affect the use of orthosis such as patients’ diagnosis, demographic data, clinical characteristics, ambulation levels, medical, aesthetic-psychological concerns, functionality and device- related causes were evaluated. Results: There were 68 (61.3%) patients using the orthosis as recommended, 19 (17.1%) patients using it differently than recommended, and 24(21.6%) patients who stopped using it. Age, sex, patients’ diagnosis, disease duration, wheelchair use, orthosis type, spasticity status, etiology of stroke, functional ambulation scale, Brunnstrom stage, etiology of SCI, ambulation level, ASIA staging, complete or incomplete lesion of SCI patients, type of involvement for CP patients, Gross Motor Function Classification System scores did not have a statistically significant effect in orthosis use. The elapsed time for orthosis prescription and device related reasons were found to be statistically significant for the continuity of orthosis usage (p˂0.05). Conclusion: According to the findings in our study, the most important factors affecting the use of the orthosis were devicerelated causes and the duration of the orthosis prescription. Therefore, the prescribed orthoses should be suitable for the patient, light and easy to use. Abandonment of orthosis can be prevented by a multidisciplinary approach, regular follow-up and, if necessary, appropriate modifications to the device.