Objective: This study aimed to conduct a unified analysis comparing the clinical characteristics, disease progression, and treatment responses of pediatric-onset multiple sclerosis (POMS), adult-onset multiple sclerosis (AOMS), and late-onset multiple sclerosis (LOMS) patients., Methods: Utilizing a retrospective cohort design, we analyzed the records of 269 patients from MS clinics and categorized them into the POMS (<18 years), AOMS (≥18 and <50 years), and LOMS (≥50 years) groups based on age at diagnosis. Data collection focused on demographics, clinical manifestations, disability scores, MRI findings, and treatment outcomes., Results: Our findings indicate that while there was a consistent female majority across all groups, distinct smoking habits and differences in disease onset and progression were observed. Disease onset showed substantial differences, with 38.5 % of LOMS patients having a progressive onset. Disability scores increased from the POMS to the LOMS, with a baseline mean EDSS score of 1.81, and the LOMS group had the highest current EDSS score of 3.33. The ARR was greater in the LOMS group. Brainstem and spinal cord lesions were more common in patients with POMS and LOMS, but the difference was not statistically significant. Among those tested, 89.6 % showed OCB positivity. There was a notable shift toward second-line therapies, especially among LOMS patients, with 49.1 % achieving disease control with their initial DMT. Disease control was achieved by 59.7 % of the POMS patients, 47 % of the AOMS patients, and 38.5 % of the LOMS patients. Progression independent of relapse activity (PIRA) was observed in 19.7 % of patients, with higher second-line treatment requirements and higher EDSS scores in the PIRA group., Conclusion: Significant differences in clinical profiles and treatment responses among POMS, AOMS, and LOMS patients underscore the necessity for age-specific management strategies for MS, emphasizing the unique challenges faced by LOMS patients., Competing Interests: Declaration of competing interest The authors have no relevant financial or non-financial interests to disclose., (Copyright © 2024 Elsevier B.V. All rights reserved.)