COVID-19 is a disease caused by a new coronavirus derivative, 'CO' taken from coronavirus, 'VI' virus, and 'D' disease (disease). The outbreak of this disease has shaken the world community so much that almost 200 countries in the world have been infected by this virus, including Indonesia. To reduce the number of COVID-19 sufferers, an expert system is needed that can carry out the process of identifying the symptoms of COVID-19 so that it is easier for patients to identify the type of COVID-19 they are suffering from and not make mistakes in the treatment process. Based on this background, researchers are interested in designing an expert system application that can assist the COVID-19 diagnosis process and can be used for public services such as health centers, clinics, and hospitals. The method used by researchers in designing this expert system is the case-based reasoning method. CBR is an approach to solving a problem based on solutions to previous problems. CBR has four process stages: retrieve, reuse, revise, and retain. From the results of testing six important features in the application involving five application users using the Blackbox Testing method, a testing percentage of 98.9% was obtained, which means that the application test results are in accordance with the user's wishes, and this application is expected to help in identifying patients with COVID-19 symptoms.