The goal of the present research is the evaluation of the real cost of an Intensive Care Unit (ICU), one of the largest tertiary hospitals in Greece, and to make a comparison to the corresponding revenues that came from the pricing according to the Uniform Regulation of Health Services (EKPY) of the National Organization for the Provision of Health Services (EOPYY). The comparison of data is from the years 2019-2021, so as to evaluate the effects of the COVID-19 pandemic on ICU costs. According to ΕΚPΥ, the pricing system of Greek public hospitals is based on the Closed Consolidated Hospitalization (ΚΕΝ), which is a simplified version of the internationally acclaimed Diagnosis Related Groups (DRGs). The bibliography has shown the problem of non-correspondence between the real cost of health services and the cost by which hospitals are reimbursed. This inconsistency, based on our research, is present in the ICUs as well, which absorb a large number of a hospital’s expenses as their operation requires very accurate specifications. In order to estimate the real cost, the microcosting model was used. From the analysis of the cost data, it was found that the daily cost of an ICU in 2019 greatly falls behind the daily reimbursement based on the KEN. Additionally, it is even higher during the next 2 years when the emergence of COVID-19 skyrocketed both the need for ICU hospitalization and its daily cost, without adjusting the daily reimbursement. In order to apply the model of micro-costing and to evaluate the real cost there should be a cost monitoring system for the fluctuations of the necessary cost data in public hospitals. The introduction of a new accounting system in the public sector, which incorporates the International Public Sector Accounting Standards (IPSAS), the European Systems of Accounts (ESA 2010) as well as the functional classifications of accounts by which the sectors of cost data will be defined according to the COFOG (Classification of the Functions of Government) will give the possibility to monitor all the necessary cost data so as the micro-costing model can be applied, which will lead to the estimation of the actual cost.