RESUMO
At present numerous Kampo formulae are used in Japan, and how we classify Kampo formulae into groups has become an important issue. Nevertheless, in recent-year Kampo formularies or prescription manuals, there is almost no comprehensive classification of all Kampo formulae covered by the older <i>Koho </i>or <i>Goseihou </i>schools, or recent Chinese Medicine. Furthermore no research has been performed on Kampo formulae classi fications. From a historical point of view, however, many classifications were made in formularies and prescription manuals of the Edo period then the early Showa period.<br>Kenzo Okuda, who belonged to the <i>Koho </i>School, was a Kampo physician in the early Showa period who attempted to make classifications of Kampo formulae. In this review, we researched his classifications as based on <i>Ruihou</i>-classifications, in other words the systematic collecting Kampo formulae by points of similarity between herb formations. Then we also studied the history of <i>Ruihou</i>-classifications preceding Okuda’s, and considered problems lying ahead for classifications of Kampo formulations in Japan.