Introduction Participatory programs for occupational risk management are becoming more important in small workplaces in developing countries such as Peru. The current legislation on occupational health and safety (OHS) in Peru is more focused on occupational exposure in big enterprises, however. In small construction companies, workers have significant high-risk occupational exposure to suffer accidents and diseases related to physical, locative, ergonomic and mechanical factors. Most of these companies do not have an OHS system adapted to their reality.

Objectives The purpose was to describe the implementation of the OHS System and its progressive improvement during 3 years in a small construction company in Peru and to show how it turned out to be a good investment and a competitive advantage.

Methods This research was a case report study. The unit of study was the economic indicators of expenses and income of a small construction company, related to OHS activities as training programs, involving workers in safety inspections, performing medical examinations for workers, performing internal audits, among others. Besides, the impact of the system on the frequency of accidents and illnesses among workers, on absenteeism, on labour inspections, on getting clients, etc. was analyzed. The instrument used was a data collection sheet. A database was created in Microsoft Excel 2007. SPSS software package was used.

Results After 3 years since the OHS system implementation, the frequency of accidents was reduced by 25%. Absenteeism was reduced by 30%. The enterprise got its OHS system certified and got more clients due to its OHS standards, which implied more economic income and a worth difference compared to other companies.

Conclusion It was a good investment to implement and improve the OHS system. It is necessary to implement studies in other small enterprises in developing countries.