OBJECTIVES: This study is a description of the development of medical audit strategy as a cooperative process of continuous quality improvement in health services in the Health Insurance Program (PAS) of the Ministry of Public Health of Ecuador (MSP).  METHODS: The development and implementation of a methodology was performed, the results are described through a cross-sectional design. RESULTS: Problems were identified in the areas of full reporting of clinical information, and therapeutic aspects of coding schemes; many of these problems were invisible to the coordinators and decision makers. In the evaluation, the increase in the percentage values of evaluations around 20 points, both in the clinic as part of the legal registration and 10 months of intervention is demonstrated. CONCLUSIONS: The process of medical audit in situ is essential for the identification and resolution of problems of errors in health care; it is demonstrated by the target values of the indicators also increased by the identification of hidden information for managers