Characterization of the on-orbit modulation transfer function (MTF) for MODIS using two data sources is presented. One is the Spectroradiometric Calibration Assembly (SRCA) cross-track spatial calibration data. This data set has been acquired since MODIS's launch. The second source of on-orbit MTF validation data is high contrast imagery using coincident ETM+, ASTER and MODIS collects. The results obtained using both sources are presented. The SRCA data are acquired in the cross-track direction and show that the MTF is temporally stable. This data set does not include the aft-optics in the analysis. MTF results from the image analysis in the cross-track direction are consistent with the pre-launch estimates, but the in-track estimates are not as consistent with the pre-launch estimates.