This study aimed to estimate direct medical cost associated with COVID-19 and compare between COVID-19 severity and pre-existing condition, based on provider perspective. The study was conducted based on a retrospective descriptive study design, incidence-based approached, from 1 January 2020 to 31 December 2021 among 1,667 COVID-19 patients. The direct medical cost was collated using a bottom-up approach. The total hospitalization stays were 23,839 days with average 14.2 days per case. Data were analyzed by descriptive statistics, i.e. number, percentage, mean (standard deviation), median (interquartile range), the minimum and the maximum value. The findings revealed a total direct cost of 608,979,250 baht, the cost per admission was 362,746 baht. The direct labor cost of health personnel caring for patients with COVID-19 was 126,864 baht per admission, 68.5% of total labor cost. The direct medical cost for COVID-19 varied between the severity of COVID-19, and the highest cost was among critically ill and deceased patients was 387,914 baht per admission. The highest direct medical cost among patients with 3 pre-existing conditions and more was 220,463 baht per admission. The study on the direct medical cost for COVID-19 reflected a burden of expenses that the government needed to bear among critically ill and deceased patients caused by COVID-19, as well as patients with pre-existing conditions. The effective preventive measures, i.e. strengthening immunity among high-risk groups of people, can reduce the number of patients undergoing treatments and reduce number of severe patients, the burden of direct medical cost for COVID-19 shall be minimized accordingly.