  We have searched for sidereal variations in the rate of antineutrino
interactions in the MINOS Near Detector. Using antineutrinos produced by the
NuMI beam, we find no statistically significant sidereal modulation in the
rate. When this result is placed in the context of the Standard Model Extension
theory we are able to place upper limits on the coefficients defining the
theory. These limits are used in combination with the results from an earlier
analysis of MINOS neutrino data to further constrain the coefficients.
