We have done factor analysis to study the effects of clinical knowledge on the diagnosis process. Clinical datas were made on 94 patients with cerebrovascular accident diagnosed by computed tomographic scan and who did not over 20 days after stroke. After analysis, totally 11 factors has been found. Among these factors, we interpreted significant 5 factors as oriental-medical meaning, Factor 1 meant Han-youl(寒熱) and factor 2 meant Huh-Shil(虛實). These were exactly corresponded with clinical experience.