We studied dental complexity in Laoncistes aenigmomus to place this unique rodent species into a comparative context. The complexity of cheek teeth of Laoncistes are within the range of that for omnivorous mammals feeding predominantly on plants or that for herbivorous mammals. In a comparative sample of predominantly herbivorous hystricomorph rodents, only the degu (Octodon degus) and the chinchilla (Chinchilla chinchilla) have less complex cheek teeth than Laonastes. We also used ethanol fixed stomachs and a silicone cast of stomach of five Laonastes to study its macroscopic and microscopic gut anatomy. The stomach of Laonastes has four elongated chambers that are partially sacculated. The stomach of Laonastes differs microscopically from the typical rodent stomach: most of the epithelium is glandular, and non-glandular stratified squamous epithelium can be found only in the sulcus that is microscopically homogenous. Microscopic screenings showed that the digesta was similar in all stomach compartments. The mean renal medullary thickness (RMT) in this species is low indicating that its ability to concentrate electrolytes in the urine is low. We discuss the dentition and the stomach morphology of Laonastes in relation to observations on its natural diet.