Sweet potato varieties of different susceptibility to Meloidogyne incognita were planted in pots to examine the larval invasion of roots and the rate of development. No varieties tested were found in which the larvae failed to invade. The development rate of the invaded larvae as well as numbers of egg-sacs counted on the unit length of roots were distinctively higher in the heavily galled varieties than in the slightly galled ones. Population levels of larvae in soils from both the resistant variety “Norin No.5” and the susceptible variety “Kanto No.14” were also examined throughout one year at approximately each 10th day, with the Baermann funnel technique. A higher population was shown by susceptible varieies than resistant varieties in which only very few larvae were detected.