People with pediatric onset multiple sclerosis (POMS) may experience sensory, motor, cerebellar and cognitive dysfunctions due to the destruction of the central nervous system. These disorders can cause decrease in physical capacity, increase in cognitive symptoms and fatigue level in patients with POMS. There is no study in the literature examining the relationship between respiratory capacity and respiratory muscle strength with fatigue in POMS patients. The aim of this study is to compare POMS patients and healthy controls in terms of respiratory capacity, respiratory muscle strength and fatigue. All participants's respiratory function will be evaluated with "Minispir Light Spirometer", respiratory muscle strength with "MD Diagnostics RP Check" and fatigue with Pediatric Quality of Life Inventory (PedsQL)-Multidimensional Fatigue Scale. Evaluations will not be repeated after a certain interval.As a result of the comparison of both groups, it will be determined whether POMS patients have difficulties or not.