Abstract: The papillae of the head and tail of Ascoris lumbricoides were viewed by scanning electron microscope.En face view of the head shows three lips, one dorsal and two subventral lips. There are six internal labial papillae near the top of three lips, forming an inner labial papillar circle. Two dorsal, one ventral and one lateral papillae together with an amphid form the outer labial papillar circle.The dorsal papillae, are mounded elliptic elevations, showing a wide ventral and narrow dorsal side in shape. The ventral papillae have nearly the same size and shape as the dorsal papillae except that they show a wider dorsal and narrower ventral side. In the anterior dorsal region of the ventral papilla there is a lateral papilla and an amphid on the subventral lips. The ratio of distance between ventral papilla to lateral papilla and that between lateral papilla to amphid is 2-3:1.Precloacal papillae are arranged into two lines situated at each side before the cloaca. On one side, the beginning has 4-5 papillae arranged in a line, bifurcating later into two irregular lines. All of them appear to be a single elevation which has a mammilliform process located at the top of these papillae. There is a precloacal central papilla just at the anterior end of the cloacal lip. It is a typical double papilla.Postcloacaly, at one side, the anterior two form a pair of double papillae, the second one being smaller than the first. A round phasmidial pore is just located at the lateral side behind the second double one.It is suggested that the lips are joined two by two, i.e, the two original dorsal ones make up the dorsal lip, the four original lateral and ventral ones make up the two subventrai lips. The ventral papillae are two stalked structures, each original ventral cephalic papilla migrates anteriorly to the labial region and combines with the original outer labial papillae to form the ventral papillae. Similarly, the original outer labial and cephalic papilla at the dorsal side combine with each other to form the dorsal papilla.No obvious difference in shape and distribution of the labial papillae is found between the two species of Ascaris from man and pigs, except that the beginning of precloacal papillae arranged in a line is different. The number of these papillae in Ascaris suum is 6-7 usually, whereas that in Ascaris lumbricoides is 4-5.