Scientific elucidation of “oketsu (blood stasis)” states is very important to understanding the diagnostic methods of oriental medicine. We investigated the correlation of blood fluidity to oketsu states, by micro channel array flow analyzer (MC-FAN). Twenty-seven female patients were divided into three groups: a non-oketsu group, a mildly affected group, and a severely affected group according to the diagnostic criteria of their oketsu syndrome. Immediately after collecting their venous blood, whole blood passage time was measured by MC-FAN. And we compared and investigated the correlation with degree of oketsu state, diagnostic criteria and changes of whole blood passage time after the administration of ku-oketsu drugs. As a result, whole-blood passage time of the mildly affected group and the severely affected group were significantly longer than that of the non-oketsu group, while the [an] improvement of blood fluidity was observed after medication. This study confirms that reduced blood fluidity is seen using MC-FAN in oketsu states, and that ku-oketsu drugs are able to improve these states.