Abstract Purpose: The corpus callosum (CC) is the largest commissural pathway connecting both cerebral cortices. Materials and Methods: Forty MS patients and 40 healthy controls were included in this research, which was planned as a prospective and case-control study. Disability was evaluated with the expanded disability rating scale. The number of attacks, disease duration, and MS disease subtype were determined. CC genu, truncus, splenium, and anterior-posterior diameters were measured in brain magnetic resonance imaging TSE/T1 sagittal sequence, and the corpus callosum index (CCI) was calculated using these measurements. The relationship of all these parameters with each other was examined. Results: There were 40 patients (29 females, 11 males) with a mean age of 36.47±11.14 years in the study. In the CC morphometric measurements of the patients, the genu (mean±SD) was 11.46±1.60, truncus (median, min-max) 5.29 (4.6-6.52), splenium 11.09±1.82, anterior-posterior diameter 65.20 (63.64-67.22) and CCI was determined as 0.43±0.05 millimeters. The anterior-posterior diameter was smaller in MS patients (p=0.022). A negative correlation was determined between CCI and disease duration, the number of attacks, and EDSS scores in MS patients (p<0.05; r=-0.319; r=-0.316; r=-0.349; respectively). In the severe disability group, CC splenium, AP diameter, and CCI were lower (p=0.007; p=0.020; p=0.046; respectively). Conclusion: In MS disease, the CC structure is affected, as in many central nervous system regions. The study results revealed that changes in the corpus callosum could be examined as a parameter in evaluating the disease process in MS patients. Keywords: Multiple sclerosis; corpus callosum; morphometry; disability.