This study presents the morphology of the ovary, as well as the dynamics of the vitellogenesis process in oocytes of the diplopod Urostreptus atrobrunneus (Spirostreptida, Spirostreptidae). The oocytes are arranged in clusters called ovisacs, which are distributed in a paired way along the body. The ovary is of the panoistic type. Differently from the other species of diplopods, it was observed little calcium in the oocytes of atrobrunneus. Lipids and proteins probably have double origin, i.e, endogenous and exogenous, with probable participation of the adjacent perivisceral fat body. The polysaccharides probably have exogenous origin with participation of the follicular epithelium in the synthesis and/or incorporation of these elements. (C) Koninklijke Brill NV, Leiden, 2010.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)