The seed storage proteins of 434 strains of azuki bean, Vigna angularis (Willd.) Ohwi and Ohashi, from Japan, South Korea, Bhutan, Nepal, China (mainland) and Taiwan, were analyzed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Fifteen protein types (types I to XV) were identified on the basis of the combination of the polymorphic bands. The geographical distribution of total protein types differed among regions from where the strains originated. In Bhutan and Nepal, most strains showed region-specific types I and II, whereas a few strains had type III. Genetic variability (H’) of Bhutan and Nepal strains were 0.502 and 0.636, respectively. Four types (III, IV, V and VII) were detected in germplasm from South Korea. Of these, types III and IV were major types. They showed a genetic variability value of 0.854. All strains from China (mainland) and Taiwan belonged to type III and type IV, respectively. In Japan, 311 strains from 38 prefectures were divided into seven geographical groups, i.e., Hokkaido, North, East, Central and West Honshu, Shikoku and Kyushu. In Hokkaido, only types III and IV were detected with equal frequency, whereas type IV was dominant in other six regions. Type V strains were distributed with a low frequency in East, Central and West Honshu, and Shikoku. A small number of strains with the other nine types (VI, VIII-XV) were uniquely observed in Central Honshu, West Honshu, Shikoku and/or Kyushu. Most of these unique types were detected with the strains in the districts along the coast of the Japan Sea. Consequently, the strains of northeastern and central Japan exhibited a lower genetic variability (0.416-0.694) than those of southwestern Japan (0.619-1.286). The highest genetic variability (1.286) was found in West Honshu where 11 kinds of protein types were observed.