This study was an analysis of the retinal layer thickness in multiple sclerosis (MS) patients using spectral-domain optical coherence tomography (SD-OCT). Methods: A total of 42 patients diagnosed in the neurology clinic with MS according to the McDonald Criteria and 21 healthy individuals were included in the study and 4 groups were created. The first group comprised 21 eyes of 21 MS patients without eye involvement, the second group was made up of 21 eyes of 21 MS patients with a history of optic neuritis, the third group included the other eye of patients in the second group without a history of optic neuritis, and the fourth group was a control group of 21 eyes of 21 healthy individuals. SD-OCT was used to visualize and measure the retinal layers and the thickness was analyzed using the device software. Results: The mean age of the patient groups was 35.39±7.52 years, while it was 32.86±2.60 years in the control group. The mean duration of the disease was 9.81±6.65 years with a mean of 4.84±2.38 attacks. The ganglion cell layer (GCL) and the inner plexiform layer (IPL) of all of the patients were thinner compared with the control group in the parafoveal and perifoveal areas. All regions of the retinal nerve fiber layer (RNFL) of patients in the second group were thinner than those of the control group. The RNFL, GCL, and IPL in the central, parafoveal and perifoveal macular rings in group 3 were thinner than the group 1 measurements; however, this difference was not statistically significant. Although the RNFL, GCL, and IPL layer thicknesses were lower in group 2 than group 3, only the difference in the parafoveal GCL thickness was statistically significant. Conclusion: This study demonstrated that MS affects retinal layer thickness, and particularly the inner retinal layers.