This study aimed to clarify the use of drugs in clinics based on dispensing frequency and expenditure which greatly influence national medical expenditure. We developed a method to determine drug use based on drug dispensing frequency and expenditure. Data were collected from the electronic receipt records in the University of Miyazaki Hospital from April 1 2017 to March 31 2018. The main item of this cohort was information gathered from the national electronic receipt such as drug type, number of dispensing frequency, and expenditure of claim. Drug selection was based on ABC analysis, one of the most popular methods for inventory management. ABC analysis can visualize the importance of each drug based on cumulative rate of dispensing frequency or expenditure. There are two types of ABC ranking based on cumulative rate of drug dispensing frequency and expenditure. The total frequency was 503,383 times and USD 26,630 thousand from 2,367 kinds of drugs in the cohort. However, the skewness was 8 for the frequency and 17 for the expenditure. In particular, it was possible to extract about 50% of total number of the expenditure from only about 12 drugs with A rank. In conclusion, there was a long-tail trend in drug dispensing as same as many products in internet shopping service. Based on this trend, it would be valuable for these 12 drugs to analyze detailed relationship between them and other treatment such as a process mining.