ANALYSIS OF HOSPITAL EFFICIENCY DETERMINANTS IN CHILE Background: The knowledge of variables influencing hospital efficiency is of paramount importance to carry out initiatives of management improvement and optimization. Aim: To explore on the hospital technical efficiency factors. Material and methods: Data from 255,439 hospital discharges from 28 hospitals from May to October 2011 were analyzed. The efficiency index developed by Santelices et al was calculated. Proxy variables of hospital practices, human resource productivity, strategic performance, financing mechanisms, geographical territory and specialization, were considered. The analysis was carried out estimating econometric models. Results: The most significant variables to explain efficiency are the length of stay adjusted by complexity, the discharges per nurse and midwife and the performance of the Hospital Balanced Score Card. Conclusions: The suggested analysis contributes to identify hospital efficiency causes. The results suggest ways to improve performance of hospitals.