Two small hookworms (male and female) from the small intestine of a dog were identified as Ancylostoma kusimaense Nagayoshi, 1955, a species previously reported only from a naturally infected badger. Distinct differences occur in the relative size and disposition of the bursal rays and in the ratio of surface areas of the outer and inner buccal teeth of A. kusimaense, A. duodenale, A. ceylanicum, and A. braziliense. Thus, support is given the assertion of Biocca that A. ceylanicum and A. braziliense are distinct species. In 1955, Nagayoshi described a new ancylostome collected from badgers in Miyazaki Prefecture, Kyushu, Japan, and named it Ancylostoma kusimaense. In 1957, the present writer found two small hookworms, one male and one female, in the small intestine of one of 255 dogs in Kyoto City. Although they were finally identified as Ancylostoma kusimaense, it was noticed that this species closely resembled Ancylostoma ceylanicum and A. braziliense. In the present paper A. kusimaense is described in greater detail and compared with other hookworms which have two pairs of ventral teeth. MATERIALS AND METHODS Examined in this study were collections of A. duodenale from patients in Kyoto City, A. ceylanicum and A. braziliense from dogs in Ceylon (kindly supplied by Dr. A. S. Dissanaike), A. kusimaense from badgers in the type locality (supplied by Dr. Nagayoshi), and the two specimens from a dog in Kyoto City. All of the specimens were preserved in 3 to 4% formalin or 70% alcohol. In the following descriptions measurements are in microns unless otherwise indicated.