The microvascular architecture of the fungiform, vallate and foliate papillae was investigated under scanning electron microscope in man, common squirrel monkeys, common marmosets, common tree shrews (primates), large Japanese moles and dwarf shrews (insectivores) utilizing microvascular corrosion casts. The fungiform papilla of the lingual apex in man was supplied by an intrapapillary capillary network with a globular pattern. It was composed of 10-15 capillary loops in a circular arrangement and 5-7 thick capillaries in the center. The fungiform papilla of the lingual body was supplied by a dense capillary network on the top and lateral surfaces. That in other primates was supplied by a cylindrical capillary network and loop formation was seen on the top surface. That in insectivores was supplied by a thin cylindrical network with coarse meshes, at the tips of which were observed 2 or 3 capillary rings in the mole and only one in the dwarf shrew. The vallate papilla in primates was supplied by an intrapapillary capillary network with a globular pattern, and showed irregularly tortuous capillary loops on its top surface. The vallum was supplied by a capillary network in man and usually one or two rows of loops arranged in a circle in other primates. The vallate papilla in insectivores was supplied by a doughnut-like capillary network with a recess on the top surface, and an indistinctly low vallum by a low undulating network. The foliate papillae were most developed in man, and each lobule was supplied by capillaries passing longitudinal to it and capillary loops in 5-10 regular rows on the top, but 3-5 rudimentary lobules in the squirrel monkey and marmoset. In the two species, each lobule was supplied by one arteriole, one venule and a coarse capillary network continuing from the interpapillary network. No foliate papilla was observed, but large conical papillae were noted in the tree shrew and insectivores. In conclusion, the intrapapillary vasculature appeared most complicated in man, simplified in the squirrel monkey and marmoset, and was much more simplified in the insectivores, where it was quite different from that in the primates. The pattern of the intrapapillary vasculature in the tree shrew was transitional between primates and insectivores.