Background: Avoidable mortality (AM) is one of the most important health indicators (HI) and represents the quality of care in a hospital. Objective: This study measured the efficacy of a training program for a hospital healthcare staff to reduce AM. Methods: This epidemiological study on community intervention analyzed time-series data on HI by semesters from 2008 to 2015. The pre-intervention phase was examined from January 2008 to December 2014; the intervention phase was investigated in the first semester of 2015; and the post-intervention phase was examined in the second semester of 2015. Results: Resindicate a series with a rising tendency until the 14th semester and a pronounced descent in the 16th semester. The relative variation rate (RVR) was -20% to +20% with some exceptions. HI was 0.53% in the 16th semester rather than the expected 0.70% observed in the pre-intervention phase; therefore, 0.17% additional deaths were avoided because of the training seminar. Conclusion: The positive results suggest that this strategy is an important element in decreasing avoidable deaths in hospitals.