Objective To investigate and analyze the usage of medicines in an outpatient clinic in 2018 so as to provide reference for rational drug use in this clinic.Methods Data on the delivery status of drugs in 2018 was retrieved from the health information system of this clinic. The consumption and variety of medicines in general and class A drugs in particular were subjected to ABC analysis.Results There were 61 types of class A drugs that accounted for 16.14% of the varieties of medicines used and 74.27% of the consumption sum, compared with 68, 17.99% and 16.47% for class B drugs, and 249, 65.87% and 9.26% for class C drugs. Most of the class A drugs were Chinese patent medicines and cardiovascular drugs. The cumulative percentage of two drug varieties was 50.82% and that of consumption was 61.82%. Both accounted for more than 50%. The percentage of major drugs among Chinese patent medicines was 23.44%,compared with 76.56% for the adjuvant drugs. There were a total of ten types of cardiovascular drugs used, six of which were antihypertensive drugs.Conclusions The usage of cardiovascular drugs is basically rational in this outpatient clinic, but that of adjuvant drugs from Chinese patent medicines is not. This is an urgent issue to be solved so as to promote rational drug use.