Objective. To identify the factors associated with the non-reporting of adverse events in diagnostic support services in a primary level of care, in order to make decisions aimed at providing a safe care to its users. Materials and methods. This research corresponds to a retrospective descriptive, exploratory study. Based on the analysis of the records of the management and follow-up records of adverse events not reported in the institution’s patient safety program, during the period from January 1, 2010 to December 31, 2015. Results. 46.5% of adverse events in the clinical laboratory service and 45% of adverse events in the diagnostic imaging service during the study period were not reported by default; situation that affects the safety of the patient indicating a poor culture on the report of adverse events. Conclusions. The highest percentage of unreported adverse events in diagnostic support services during the study period was not carried out of fear, this situation was attributed to the staff involved fearing that punitive actions were taken as a consequence of the presentation of these events.