ABSTRACT Objectives: to analyze vaccine losses in a Health Region in the Northwest of São Paulo. Methods: retrospective cross-sectional study with secondary data obtained from Temperature Change Notification Forms used by the Epidemiological Surveillance Group XXIX of São José do Rio Preto between 2010 and 2017. Descriptive and inferential analysis were performed using multiple linear regression and significance level of 95%. Results: in total, 341 notifications of temperature changes were analyzed, of which 70.1% were caused by structural reasons, 57.8% in industrial refrigerators and 91.2% in primary care services. Of the doses that suffered a change in temperature, 41.4% were lost and 58.6% were administered to the population. The highest percentage of lost doses compared to those applied occurred in smaller municipalities, although they reported less. Conclusions: nursing workers who work in vaccination rooms should make efforts to prevent temperature changes and avoid losses and higher public expenses.