The analysis of the national and international literature reveals a prevalence of around 20% of work-related musculoskeletal disorders in construction workers over 40 years of age. The chronic-degenerative disease in the muscular-skeletal system is important not only for the number of reported cases, but also for the seriousness of the symptoms, which are one of the main causes of evaluations of limited work-suability and unfitness for work. The aim of this study is to improve the quality of the diagnosis of occupational musculoskeletal illnesses and to ensure that the occupational physicians identify such disease, as prescribed by the Italian legislation about safety and health in workplaces. The research involved 57 construction companies located in the Bergamo's province, which employ, in aggregate, 833 workers. A sample of 479 workers, 40, or more, years old (403 Italians and 76 foreigners) was analysed. It was found out that 152 workers had some musculoskeletal disorders but only for 5 of them an occupational disease was already reported. It was necessary to ask the occupational physician for further clinical investigation for 60 employees, which revealed 29 new musculoskeletal occupational diseases in 19 workers. At the end of the study a total of 34 musculoskeletal occupational diseases were diagnosed in 22 workers: it was 4, 6% of the total sample investigated (n. 479) and 14% of those who already had problems (no 152). The results confirm the under-reporting of occupational musculoskeletal diseases in construction workers. The active research is a useful tool for the purposes of verifying the level of health surveillance carried out by occupational physicians. In fact the study highlighted that physicians seem not to be inclined to require additional clinical investigations and not always report occupational diseases.