Background: Multiple sclerosis (MS) is a neurodegenerative disease, and is considered a chronic inflammatory disease. Retinal nerve fiber layer (RNFL) thickness as a structural biomarker for axonal loss in MS. Objective:  The aim of the present study was to assess the role of optical coherence tomography (OCT) in detecting RNFL in MS patients without history of optic neuritis and to correlate with disease duration and disease disability. Patients and methods: Case-control study included 34 patients with clinically definite relapsing remitting multiple sclerosis (RRMS) and 34 age- and sex-matched individuals (other than MS) served as the controls. They were selected from the inpatients wards and Outpatients Clinic of Neurology Department, Zagazig University Hospitals. All patients were subjected to full history taking, clinical examination as well as laboratory and specific investigations. Results: The mean age was 34.56 ± 8.79 years in MS patients and 34.03 ± 8.79 years in controls. VEP 42.9% is with delay of p100 wave in bilateral eyes, and prolongal p100 laterary in bilateral eyes in 54.3%. There was a highly statistical significant difference between groups as regard RNFL average thickness and RNFL symmetry. Expanded disability status scale (EDSS) showed independently associated with RNFL. Conclusion: The thickness of the RNFL observed by OCT in MS patients is dramatically reduced when compared to controls, according to the current study. OCT is a valuable tool for determining the thickness of the RNFL in MS patients.