Hospital expenditure constitutes the main component of public health spending in Western countries. Among the elements most frequently indicated as a cause of the increase in expenditure is the aging of the population. All Italian hospitalizations of more than one day during the year 2001, involving persons over 65 years of age, were analyzed on the basis of the data gathered by the Ministry of Health, starting from the hospital discharge forms. A comparison between the same data gathered for the 1996 has been carried out. The analysis reveals the impact of both the aging of the population and the use of more expensive technology on the cost increase related to 30 most frequent diagnosis-related groups (DRG) reported from the hospital disch...