In this paper, the seismic vulnerability of public hospital buildings in the central part of Tuscany Region has been analyzed: in particular, the structures inside the territory of Florence, Pistoia and Prato have been examined, investigating about 1.240.000 m³ of constructions.

The vulnerability assessment has been made by means of in-situ surveys, in order to obtain all the necessary information for the utilization of  an appropriate 2° level vulnerability form (Benedetti and Petrini, 1984; GNDT, 1993), characterized by the evaluation of eleven parameters of the building.

The obtained vulnerability index (Iv) for each building ranges between 0-100; the application of this procedure to all the buildings of  the sample (222 structural units) has allowed the creation of a classification of the most vulnerable constructions. It has been also possible to carry out the PGA of collapse simply using one correlation formula between acceleration and index of vulnerability (GNDT, 1993; Zonno et al, 1999).

After this, some buildings have been better analyzed with global structural analyses by means of three-dimensional models, obtaining the values of PGA of collapse for each of them.

The comparison between the results of the analytical models and the ones of the eleven parameters form can lead to the validation of the vulnerability index method or to the proposal of some modifications of the fast vulnerability assessment method. It will be also possible to find out a new  correlation between the index of vulnerability Iv and the PGA of collapse for the buildings.