The article describes the characteristics of elderly people living in institutions, according to the 1991 Italian population census. At the present there are no more recent data that be used to describe this population. In Italy, institutionalised people are about 1.3% of the total population aged 60 years and over. They tend to older than those who live in families; institutionalised old people are more often women are than men; they are also less educated and tend not to be married. About 50% have no living relatives. An estimate of transition probabilities from living in a family to institutionalisation is given, using different data sources: these probabilities are particularly high for those aged over 80. The level of mortality among the institutionalised is higher than that of the general population, especially in the first year, above all due to bad health at the moment of entry in the institutions. A projection of the size of the institutionalised elderly population is performed with constant prevalence rates as observed in 1991. The estimate obtained for the year 2015 is about 200 thousand people aged at least 60, that is, about 50 thousand more than those recorded in the 1991 census.