We examined 590 specimens of Reithrodontomys from 95 localities in the state of México. Four species of the subgenus Reithrodontomys and 1 of the subgenus Aporodon were identified. The former subgenus included R. chrysopsis, R. sumichrasti, R. megalotis, and R. fulvescens, which has 2 subspecies—R. f. toltecus and R. f. mustelinus—in the state. The representative of the subgenus Aporodon is R. microdon wagneri, which is recorded for the first time in the state. We give information on taxonomy, morphometrics, reproduction, habitat characteristics, and related fauna. A discriminant analysis correctly classified 100% of specimens from the 6 taxa with 5 canonical variates, and accounted for 96.1% of the variance with the first 3 canonical variates.