The first documented use of the larvae of the hairy maggot blow fly, Chrysomya rufifacies, for estimating the postmortem interval (PMI) of a decomposing human corpse in Thailand is reported. A honeycomb-like wound observed on one leg of the corpse was infested with numerous third-stage C. rufifacies larvae. Based on the pupae and larvae present in accordance with the ambient temperature previously recorded, six days postmortem was estimated for a corpse at the time of its discovery and investigation. Since adult C. rufifacies specimens have been collected in many parts of both urban and mountainous areas in Thailand, more biological information about this blowfly species is needed to increase the accuracy of forensic investigations where the fly is present.