This volume report includes the scientific results hitherto obtained from the Botanical Expeditions to Eastern Himalaya by the University of Tokyo in 1960 and 1963. The main objects of our expeditions are to make more clear the close botanical relationship between Eastern Himalaya and Japan, to investigate critically the corresponding taxa in both regions, and to analyse the process of evolution in the plant groups originated from a common ancestor in the early tertiary and now widely separated in both regions. So we have concentrated our effort to study the temperate flora of Eastern Himalaya in comparison with that of Japan. Our collections consist of about 60,000 specimens which are in many cases supplemented by field notes and coloured photographs. Moreover a large number of vascular plants were brought home as living plants and seeds, and are now cultivated in Japan for our studies.