Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; In this paper, we describe and illustrate the morphology of the first larval stage of the prawn Macrobrachium brasiliense. Two ovigerous females were obtained in a stream environment, which belongs to Paraná River Basin, Southeastern of Brazil, and were maintained in laboratory until the time of hatching. The newly-hatched larva bears very advance morphological features, with benthic habits. They had sessile eyes and all appendages, except for the uropods; however, most of the appendages were not fully formed. The description given here is compared with the first larval stage of Macrobrachium species with abbreviated larval development from other localities.