The morphology of the seminiferous tubules of dasyurid marsupials has been investigated in seven species. The tubules are large in diameter, ranging from 0·36 to 0·52 mm, and the total length of the tubules in the testis is small ( < 1 m). In dissected testes, most tubules were found to be in the form of simple loops and the number of loops ranged from one to four. Each loop had two openings into the duct draining the testis. There was only a single duct from the testis in the dasyurids examined. The large diameter, simple form and low number of tubules in the testis of these dasyurid marsupials make them unique among mammals which have been studied in this respect.