Choosing an auspicious day originated from cosmobiological concepts which were prevalent in traditional society. This method was devised to minimize the damage and maximize the effect of acupuncture and moxibustion. It is found in most of Asian traditional medicine and still regarded as important in Tibet. In Korea, historical records show that various rules were applied to make certain pills, enhance physical condition, avoid illness and to get medical care. Strict rules were also applied to avoid inauspicious days when using acupuncture and moxibustion. But this tradition lost chance of proper evaluation due to involuntary and rapid westernization. Chimgutaekilpyonjip was published in early Chosun dynasty collecting almost all existing methods from the Huangdineijing to Sung-Chin-Yuan medicine. DonguiBogam Yirimchalyo and Chimgukyunghumbang succeeded these methods in separate ways. But they are similar at particular points. In many clinical cases of Seungjeongwonilgi, most methods written in DonguiBogam were used to choose auspicious days, In this study, the characteristic of Chimgutaekilpyonjip and other medical texts of Chosun are compared by analyzing the contents regarding choosing an auspicious day. Secondly, clinical records of Seungjeongwonilgi are examined to assess their practical use. Studying and evaluating the past theories could help accelerate the procedure of setting a proper standard in our times.