A comparative study of Diptera communities associated with pig carcasses was carried out in urban and natural settings in tropical mountain habitats of Southern Mexico. Schoenly-type traps were used to set out pig carcasses during 68 d of sampling effort. In total, 1,703 adult Diptera specimens were collected in both localities combined, and recording a total of 30 (morpho) species and 19 families. Compared to natural habitats, a significantly greater diversity in urban habitats, as well as a faster decomposition process of carcasses, was detected. Significant differences were also detected for the composition and structure of Dipteran communities between urban and natural sites. Dominant species of Calliphoridae for natural and urban habitats were represented by Compsomyiops spp. and Cochliomyia macellaria (Fabricius; Diptera: Calliphoridae), respectively. The properties of indicator species for urban and natural sites are discussed. Twenty Dipteran species were significantly associated to different decomposition stages. Such affinity would allow for estimating the post-mortem interval (PMI) in comparable situations.