A preliminary study on coprophilous and necrophilous Diptera assemblages was done at family level, in a serranía forest in Sierra de Minas, Uruguay. Besides, seasonal structure variations of both assemblages were assessed. Dipterous were sampled monthly during a year, using pitfall traps baited with cow dung and cow liver, which were deployed for a week. A total of 3,142 individuals corresponding to 21 families, were captured. Heleomyzidae was recorded for the first time in Uruguay. The most abundant families were Phoridae and Sphaeroceridae which represented 58% of total number of captures. Sphaeroceridae (42%) was the dominant family in dung baited traps, followed by Cecido-myiidae (14%) and Phoridae (12%). Phoridae (59%) was the most abundant family in carrion baited traps, followed by Drosophilidae (10%). Both assemblages showed the same pattern of seasonal abundances variation, and revealed peaks in spring (October - November) and in autumn (April). The number of families of coprophilous flies was greater during spring (October-December) and in autumn (April) while necrophilous flies showed the highest richness of families only from October to November. This study represents the contribution to the knowledge about dipteran communities in native ecosystems in Uruguay.
