Background: Risky sexual behavior is a major public health concern of Ethiopians. Although studying the autonomy of women in refusing risky sex is significant to take proper actions, the issue is not yet studied. Accordingly, this population-based nationwide study was aimed at assessing the trends of women’s autonomy in refusing risky sex and its associated factors in Ethiopia.Method: The sample was limited to married women of 2011 (n=8369) and 2016 (n=8403) Ethiopian Demographic and Health Survey (EDHS) data. Women's autonomy in refusing risky sex was measured based on wives' response to 'not having sex because of husbands have other women. To examine associated factors, sociodemographic variables were computed using binary logistic regression. Result: The finding revealed that the trend of women’s autonomy in refusing risky sex had declined from 78.9% in 2011 to 69.5% in 2016. Women aged from 25-34 were less likely autonomous in refusing sex (AOR=.764;95%CI=.605,.965), in comparison with women aged less than 24 years old. The autonomy of women with primary, secondary, and higher educational status were AOR=1.607;95%CI:1.379,1.874, AOR=2.208;95%CI:1.639,2.975, and AOR=3.221;95%CI:1.647,6.300 respectively. The autonomy of women from rich households was more likely higher (AOR=1.523;95%CI:1.28,1.813) in comparison to women from poor households. The autonomy of women in Tigray, (AOR=2.938;95%CI:2.025,4.263), Afar (AOR=1.497;95%CI:1.111,2.017), Amhara (AOR=4.870;95%CI:3.388,7.000), Benishangul Gumuz (AOR=.568;95%CI:.406,.796), SNNP (AOR=1.900;95%CI:1.355,2.664), Harari (AOR=.516;95%CI:.372,.716), and Addis Ababa (AOR=3.809;95%CI:2.227,6.516) when compared with autonomy of women who resides Dire Dawa.Conclusion: The autonomy of women in refusing risky sex has declined from 2011 to 2016. This infers that currently, women are more victimized than previously. Hence, possible interventions like empowering women shall be taken to protect women from certain health problems of risky sexual behavior.