CMRR

CMRR may stand for:


 * Catskill Mountain Railroad, operators of the former New York Central Railroad Catskill Mountain Branch from Kingston to Phoenicia
 * Central Massachusetts Railroad, former railroad forming part of the Boston and Maine Railroad system
 * Common-mode rejection ratio, measure of the capability of an instrument to reject a signal that is common to both input leads
 * Chemistry and Metallurgy Research Replacement Facility, nuclear facility at Los Alamos National Laboratory