The decomposition of small carcasses in the open is frequently neglected although it may provide information of forensic importance. This paper describes an experimental study of arthropod species associated with carcasses of mouse, Mus musculus (Linnaeus, 1758) and rat, Rattus norvegicus (Berkenhout, 1769) (Rodentia: Muridae). Four carcasses were left inside iron cages in sunlit and shady areas in a secondary forest in Southeastern Brazil twice a season for four seasons (n = 16 carcasses of each rodent). The carcasses were removed when arthropods ceased to visit them. The visiting and colonizing invertebrates were collected daily and identified. Immatures were also collected and reared in a laboratory for identification. We collected 6,514 arthropods (820 adults and 5,694 juvenile forms) belonging to 53 species from the families Sarcophagidae, Calliphoridae, Muscidae, Fanniidae, Syrphidae, Richardiidae, Sepsidae, Micropezidae, Otitidae, Drosophilidae, Phoridae, Dolichopodidae, Anthomyiidae, Asilidae and Lauxaniidae (Diptera), Formicidae, Ichneumonidae, Encyrtidae and Apidae (Hymenoptera), Staphylinidae (Coleoptera) and Gonyleptidae (Opiliones). Lucilia eximia (Wiedemann, 1819) (Diptera: Calliphoridae) and Peckia (Pattonella) intermutans (Walker, 1861) (Diptera: Sarcophagidae) deserve special attention because both adult and immature forms were collected in all seasons and in both areas. Our results indicate that the frequency of occurrence of these arthropods was positively associated with carcass size (mouse or rat); no marked insect succession on the carcasses occurred; and the diversity of Calliphoridae and Sarcophagidae was high, irrespective of season.1054691696BAUMGARTNER, D.L., GREENBERG, B., Distribution and medical ecology of the blow flies (Diptera: Calliphoridae) of Peru (1985) Ann. Entomol. Soc. Am, 78, pp. 565-587BORNEMISSZA G.F. 1957: An analysis of arthropod succession in carrion and the effect of its decomposition on the soil fauna. Aust. J. Zool. 5: 1-12BUGG, R.L., DITCHER, J.D., Warm-season cover crops for pecan orchards: Horticultural and entomological implications (1989) Biol. Agric. Hortic, 6, pp. 123-148CARVALHO, L.M.L., THYSSEN, P.J., LINHARES, A.X., PALHARES, F.B., A checklist of arthropods associated with carrion and human corpses in southeastern Brazil (2000) Mem. I. Oswaldo Cruz, 95, pp. 135-138CARVALHO, L.M.L., LINHARES, A.X., Seasonality of insect succession and pig carcass decomposition in a natural forest area in southeastern Brazil (2001) J. Forensic Sci, 46, pp. 604-608CORNABY B.W. 1974: Carrion reduction by animals in contrasting tropical habitats. Biotropica 6: 51-63GILLIAM M., LORENZ B.J. & RICHARDSON G.V. 1988: Digestive enzymes and micro-organisms in honey bees, Apis mellifera: Influence of streptomycin, age, season, and pollen. Microbios 55: 95-114HANSKI I, CPrrion fly community dynamics: Patchiness, seasonality and coexistence (1987) Ecol. Entomol, 12, pp. 257-266KOČÁREK P, A pitfall trap for carrion ecology studies (2000) Biologia, 55, pp. 575-577LAUBERTIE, E.A., WRATTEN, S.D., SEDCOLE, J.R., The role of odour and visual cues in the pan-trap catching of hoverflies (Diptera: Syrphidae) (2006) Ann. Appl. Biol, 148, pp. 173-178LINK, D., STORCK, L., CERVI, J.A., PADOIN, A.J., GIULIANI, D., Occurrence of the fly Euxesta sp. on sweet corn at Santa Maria, RS (1984) Ciência Rural, 14, pp. 93-99LUDWIG, J.A., REYNOLDS, J.F., (1988) Statistical Ecology: A Primer on Methods and Computing, , John Wiley, New York, 368 ppMONTEIRO-FILHO, E.L.A., PENEREIRO, J.L., A study on decomposition and succession on animal carcasses in an area of São Paulo, Brazil (1987) Braz. J. Biol, 47, pp. 289-295MOURA, M.O., MONTEIRO-FILHO, E.L.A., CARVALHO, C.J.B., Heterotrophic succession in carrion arthropod assemblages (2005) Braz. Arch. Biol. Techn, 48, pp. 477-486NORRIS K.R. 1965: The bionomics of blowflies. Annu. Rev. Entomol. 10: 47-68OLIVEIRA-COSTA, J., MELLO-PATIU, C.A., LOPES, S.M., Muscoid Diptera associated with human corpses at the death scene in the State of Rio de Janeiro, Brazil (2001) Bol. Mus. Nac. N.S. (Zool.), 464, pp. 1-6PAYNE J.A. 1972: Insects succession and decomposition of pig carcasses in water. J. Georgia Entomol. Soc. 7: 153-162(1988) SAS/STAT User's Guide. Release 6.03, , SAS INSTITUTE INCORPORATION, Ed. Cary, North Carolina, USASOUZA, A.M., LINHARES, A.X., Diptera and Coleoptera of potential forensic importance in Southeastern Brazil: Relative abundance and seasonality (1997) Med. Vet. Entomol, 11, pp. 8-12