In order to obtain basic information regarding improvement of potato root characters through breeding using its wild relatives, morphology, respiration activity, dry weight (DW), length and surface area of the roots of 12 potato cultivars and lines and 8 wild relatives (Table 1) were investigated during the flowering stage under field conditions. The roots of the wild potato species were thinner but their dry matter percentages were higher than those of the cultivars and lines (Table 2). From observation of root monoliths (Fig. 1), it appeared that the number, diameter and length of the lateral roots differed among the materials (species) used. The cultivars exhibited relatively high root respiration rata compared to the wild species on the basis of either root DW or root length (Table 2). Some wild species had a considerably larger root DW, root length and root surface area, and higher ratio of root DW to leaf DW than the cultivars and lines (Table 2 and 3). From the results it can be seen that some wild species have good potential to be used as parents in the breeding for the improvement of root characters in potato.