In this article present results of measurements for refractive index profile of silica graded multimode optical fibers are presented. The measurement technique is described. Estimation of parameters for profile defects of investigated samples of multimode optical fibers is received. Analysis data for effect of profile defects of graded multimode optical fibers (MMF) on differential mode delay (DMD) is presented.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.