Background: Background: Optic nerve inflammation may contribute to the pathology of multiple sclerosis (MS) (retrograde trans-synaptic degeneration) However, within the past ten years, some investigations have indicated that primary retinopathy may be brought on by MS. This study used a full-field electroretinogram to test the function of the outer retinal layers in people with relapsing remitting multiple sclerosis (RRMS) (ff-ERG). Methods: This is a case- control study, conducted on 30 RRMS patients and 30 healthy controls. RRMS patients were subjected to neurological, ophthalmological, and radiological assessment. Both RRMS patients and controls were subjected to full field ERG. Results: The ff-ERG showed a significant delay of latencies of a and b-waves of both light and dark-adapted condition with reduction of their amplitudes compared to control. ERG responses were significantly affected in MS patients with or without optic neuritis compared to control. Most of ff-ERG parameters showed non statistically significant difference between optic neuritis and non-optic neuritis eyes. Conclusion: There is functional affection of the bipolar and the photoreceptors layers in the outer retina in optic neuritis and non-optic neuritis eyes of MS. Therefore, the outer retina could be a site for primary pathology in MS, unrelated to the optic nerve affection.