For the purpose of developing Korean Herbalogy with the plants of Polygonaceae which grow wild and is planted in Korea, the these and writings on herbalogy, from literature of successive generations, have been thoroughly investigative and the results obtained were as follows: 1. According to nature and flavour of medicinal plants, they were classified into cold, cool; 23 each, warmth, heat; 11 each, balance 11 and unidentified 5. Thus it was noticed that cold, cool is the main in nature and flavour of medicinal plants. 2. According to the Properties and Principal curative action, they were classified into drugs for clearing up heat and toxin 18, drugs for regulating the fellow of Gi to alleviate pain 14, drugs for removing heat from the blood to stop bleeding 13, drugs for expelling wind and removing dempness 11, drugs for parasiticide 11, drugs for promoting blood circulation to remove blood stasis 10, drugs for strengthening the spleen and stomach 10, drugs for inducing diuresis to alleviate edema 9, drugs for improving acuity of vision 5 and drugs for tonifying and nourishing 4. Thus it was noticed that durgs for clearing up heat and toxin was the main kind. 3. Comparing to whole medicinal plants 47 kinds, toxic durgs include minor toxin were 12 kinds, 25% of the whole. Thus toxic durgs were slightly poisonous. From this result, it was revealed that the plants for medical purpose in Polygonaceae was 30% of the whole, in which drugs for clearong up heat and toxin was mostly abundunt and toxic plants was slightly poisonous. It is considered that many experiements and clinical approaches must be continued widely about slightly poisonous drugs.