The Italian Institute for Occupational Prevention and Safety (ISPESL) carried out a register of enterprises operating in industry, services and agriculture sector to provide information on their location, economical activity and occupational data. This database has been built merging administrative files from the National Institute of Social Security (INPS) and the Computer Science Society of Italian Chambers of Commerce (InfoCamere). Enterprises have been classified by economic sector - in accordance with ISTAT (National Statistics Institute) "Ateco91" classification--and by accuracy level of the record linkage. In details, three different subsystems have been set up: (A) enterprises satisfying linkage; (B) enterprises in InfoCamere file not linked with INPS file; (C) enterprises in INPS file not linked with InfoCamere file. In the whole, 6.026.676 factories have been collected, of which 1.188.784 in group A, 4.543.091 in group B and 294.801 in group C. Establishing a database of information on industries may be useful to improve preventive programs and to plan health care surveillance systems.