In recent years the costs of hospital care in developed countries absorbed a high proportion of total health resources. In Greece, after the establishment of the National Health System (NHS), funding for hospitals comes mainly from the state budget, and social insurance, therefore auditing of hospital cost is imperative to ensure their viability, especially at this time when the country is tested by economic crisis. Overtime many factors for the increase of hospital cost have been mentioned, such as the rapid development of medical technology, the low level of organization of the hospital system and the low productivity of human resources. The problem of rising health expenditure over the past decades is a worldwide phenomenon and it has brought about many changes in traditional retrospective methods for financing in the hospital sector, with prospective financial forms that combine patient composition and needs, and the productive activity of hospital need to the rationalization and contain expenditures. The system of Diagnosis Related Groups was a revolutionary success over the past decades and has now achieved worldwide recognition.