Objectives: Multiple sclerosis (MS), which is known as a young-adult age disease, is called late-onset MS (LOMS) when it occurs at the age of 50 and older. In our study, we aimed to analyse the clinical and demographic characteristics, comorbidities, diagnostic and treatment challenges and prognosis of LOMS. Methods: In a retrospective analysis of 136 patients diagnosed with multiple sclerosis (MS) after the age of 50, based on the 2017 McDonald criteria, and who were under observation in eight distinct MS centers across Turkey; demographic information, clinical characteristics of the disease, oligoclonal band (OCB) status, initial and current Expanded Disability Status Scale (EDSS) values, administered treatments, and the existence of spinal lesions on magnetic resonance imaging (MRI) were investigated. Results: The mean age of the 136 patients was 60.96±6.42 years (51–79), the mean age at diagnosis was 54.94±4.30 years, and 89 (65.4 %) of the patients were female. Most of the cases, 61.1 % (83) had at least one comorbidity. In 97 patients who underwent lumbar puncture (LP), OCB positivity was observed in 63.6 %. In 114 patients (83.8 %), spinal lesions were detected on MRI. Eighty-seven patients had relapsing-remitting MS (RRMS) (64 %), 27 patients had secondary progressive MS (SPMS) (19.9 %), and 22 patients had primary progressive MS (PPMS) (16.2 %). The mean EDSS at the time of diagnosis was 2.44±1.46, and the mean current EDSS was 3.15±2.14. Conclusions: In LOMS patients, the rates of delay in the diagnostic process, treatment disruption and progressive disease are higher than in the general MS population. The high rates of LP applying and OCB positivity of this study may indicate the habit of looking for clear evidences in advanged age in our country. This situation and comorbidities may cause a delay in diagnosis and eliminates the window of opportunity for early diagnosis. Although the high number of spinal lesions is a known marker for progressive disease, it is an issue that needs to be discussed whether the increased frequency of progressive course at older ages is due to the nature of the disease or immune aging itself.