Roads affect wildlife in many ways, with roadkills probably the most conspicuous. In Mexico, there is increasing interest in this effect on wildlife. Together, richness and abundance can be used to predict trends for wild populations, and our study analyzes these variables for rodents killed by vehicles and trapped along a 14-km stretch of an A-type roadway in Veracruz, Mexico, from June 2010 to March 2011. Our study area had 2 habitat types: shrubland on lava flow and grassland. Over the course of the study, we monitored this stretch of highway by car for 34 days of effective sampling. When we spotted an animal, we stopped to record it. In the surrounding habitats, traps were set for 28 nights with 36 traps per habitat (total effort: 1,008 trap nights). The richness of trapped rodents was 9 species and for roadkills it was 14. The 2 sampling methods shared 7 species. The differential contribution was 2 species in trapping and 7 in roadkills. The complementarity index was 99.36. For both methods, the dominant species were mice of the genus Peromyscus (Peromyscus difficilis for the shrubland and Peromyscus maniculatus for the grassland). Roadkills were a very representative source of information for the purposes of biological inventory and even for identifying the dominance pattern in species composition, thus offered a useful method for supplementing information obtained from traditional trapping. Highways threaten biodiversity mainly because they fragment habitats and further expose other habitats to impact by humans, but also because of their potential as a direct mortality factor. Careful interpretation of roadkill data can be a useful tool whose value for biologists has not yet been fully appreciated.