Knowledge about material properties is of fundamental importance in order to increase the reliability of structural vulnerability assessment of existing Reinforced Concrete (RC) buildings. In this study, a statistical analysis of mechanical characteristics of reinforcing bars used in Italy between 1950 and 1980 is presented, based on a large number of archive data from the steel testing laboratory of the Department of Structural Engineering at the University of Naples Federico II. Considered parameters include yield and ultimate strength and ultimate strain. Moreover, collected data allow to estimate the spread of different reinforcement typologies (such as plain or deformed bars and commercial typology) across the observed time period. Most probable values and corresponding dispersion measures are estimated according to the typology and the year of interest. Provided data can be usefully employed in the assessment of RC buildings, especially when a poor knowledge level is present, such as, for instance, in large scale seismic vulnerability assessment procedures.