Women's autonomy in health care decision-making is very crucial for the well-being of women themselves, their children, and the entire family members. Although studying the issue is significant to take proper interventions, the issue is not studied at a nationwide level in Ethiopia. Accordingly, this population-based nationwide study was aimed at assessing the trends of women’s autonomy in health care decision-making and its associated factors in Ethiopia. The sample was limited to married women of 2005 (n = 8617), 2011 (n = 10,168), and 2016 (n = 9824) Ethiopian Demographic and Health Survey (EDHS) data. Women's autonomy in health care decision-making was measured based on their response to the question ‘person who usually decides on respondent's health care. To examine associated factors, socio-demographic variables were computed using multinomial logistic regression. The finding revealed that the trend of women’s au