Leopoldamys neilli is a Murinae rodent endemic to limestone karst of Thailand and the Lao PDR, but its ecology and the reasons of its endemism to karst are still totally unknown. The aim of this pilot study was to examine the plant composition of the diet of L. neilli at the level of order and family using DNA for molecular identification and to compare it with two other forest-dwelling Leopoldamys species, L. herberti and L. sabanus. A 202bp fragment of the rbcL gene was amplified and sequenced for twenty-three fecal samples of the three species using 454 pyrosequencing. We successfully identified a total of seventeen orders and twenty-one plant families, corresponding to thirty-three putative species, in the feces of these three Leopoldamys species. Solanaceae were the most common plants in the diet of L.neilli regardless of the region and sampling season, and they were also present in feces of both L. herberti and L. sabanus. The Araceae, Fabaceae, and Apocynaceae families were also identified in feces of L. neilli collected in various regions of Thailand and at different seasons. Plants of the Oleaceae family are consumed by both L. herberti and L. sabanus but were not found in the diet of L. neilli. Further improvements of the study, such as the use of additional genes, the creation of a reference collection, the microhistological examination of plant fragments to determine which parts of the plant are consumed, and the analysis of the animal diet of Leopoldamys are suggested to enhance the quality and accuracy of the results obtained.