To grasp the idea about how drugs are used under Medical Insurance Scheme, the amount and share of drug cost in the total medical fee have been reviewed and analyzed for different types of patients (in-patient out-patient), medical institutions and frequently seen diseases and following findings were revealed. In 1986, drug cost took 32.78% of total medical fee for in-patients and 32.98% for out-patients averaged over 30% share as a whole. When drug cost per case in 1980 be indexed to 100, it has shown steady growth to become 200 for in-patients and about 150 for out-patients in 1986. The contribution of drug cost to the total medical fee is, regardless of patient type-in-patients and out-patients, the highest in University hospitals and followed by General hospitals, Hospitals and Clinics in decending order That for the most frequent 10 diseases came out the highest,79 a with the essential benign hypertension of out-patients in the General hospitals, 61% for the gastric ulcer of out-patients in Hospitals and 33% for the female genital diseases of out-patients in Clinics. The drug cost of oral formula was contributed the most, 7.93% by cardiovascular agents followed by hepatic detoxicants(5.47%) and out-patients(4.93%), and that of injectable formula was contributed the most by antibiotics(24.17%), followed by protein amino-acid preparations(6.19%). The order of drug usage by specialty for the in-patients was the highest with internal medicine followed by general surgery and E.N.T, and that for the out-parients was in the order of Internal medicine, neuropsychology and Ob/Gy. This study revealed that the drug dependency was characteristically different to specialty. In view of the fact that drug cost on average exceeds over 30% of total medical fee, proper drug administration appears to be vitally important for the stabilization of the financial standing of the Medical Insurance Scheme. As a consequence, drug usage guidelines including antibiotics usage shall be established first of all and the voluntary participation for the regulation of drug usage and propagation of the guidelines to medical institutions are strongly coerced.