Objectives : This paper aims to examine the clinical meaning of treating with sweet medicinals where acupuncture fails, through studying the verse, "In case of both Yin and Yang deficiency, treat with sweet medicinals" in the Huangdineijing. Methods : Related contents in the chapters 「邪氣藏府病形」, 「根結」, 「終始」, 「經脈」, 「九鍼論」 of the Lingshu were analyzed threefold. The circumstances of the application of the "In case of both Yin and Yang deficiency, treat with sweet medicinals" principle to the late Han East Asian medicine as written in the Shanghanzabinglun were examined, and its meaning was explored. Results : The 'Yin Yang' in the verse could be substituted with the Five Zhang and Six Fu, Blood and Qi, Form and Qi, Form and Jing, Form and Zhi, etc. In patients with deficiency in Qi, Blood, Yin and Yang, we can observe external symptoms such as narrow pulse pattern, symptoms in the throat or below the throat, thirst, and coarse voice. To apply sweet medicinals is to supplement the Jing from food, Spleen and Stomach, Middle Qi and Earth Qi which produces and maintains Qi, Blood, Yin and Yang. Therefore, it is essential in treating disease patterns with deficiency in both Qi, Blood, Yin and Yang, and cannot be substituted with other means of treatment such as acupuncture, moxibustion, and other manipulative therapies. Conclusions : Sweet medicinals were applied in disease patterns with throat thirst and narrow pulse patterns which could not be managed with general acupuncture or moxibustion in the time of the Huangdineijing's publication, as it holds the Earth virtue which could harmoniously supplement the body's Qi, Blood, Yin, and Yang. Later its application broadened, treating various conditions accompanying Qi, Blood, Yin, Yang deficiency, which expanded potential of medicine and contributed to the generalization of drug treatment.