This article consists of five parts. Part one points out the traditional Chinese medical doctors believed that evil ch'i (氣) from outside attacked the body and caused the illness. In Part two, the author points out that the medical doctors in Eastern Chin dynasty also believed that the evil ch'i invaded the feet and passed to the abdomen and heart, causing swollen feet (oedema), weakness of feet, fever, diarrhea, and finally problems in the nervous system. They mistakenly thought that it was a southern regional illness. In the T'ang Dynasty, the medical doctors had already known that this illness did not exist exclusively in the southern region, and that there were two kinds of symptoms: swollen (oedema) and non-swollen. Part three points out that according to modern medical knowledge, beriberi was due to the lack of Vitamin B1. since the Eastern Chin Dynasty, the shih-ta-fu (士大夫) changed their diet to southern well-milled rice and tea, thus, reducing the ingredient of vitamin B1 and causing the problem. Part four compares the understanding of beriberi between traditional and modern medical doctors. For the healing methods, the Chinese medical doctors might not know that the illness was due to the lack of vitamin B1, but they had already used those herbs that consisted of vitamin B1 as medicine for the illness. Part Five concludes that after the efforts by Chinese medical doctors, as well as medical knowledge being widely known by the public, by the Sung Dynasty, beriberi was no longer a fatal illness.