Background: Decision making power of women is one of the essential factors which have influence on maternal health service utilizations. Women’s lack of decision over reproductive health service utilization affects their protection from unwanted child bearing, unsafe sex and their consequences. Objective፡ Assess decision-making power on RH-service utilization and its associated factors among married women in Illubabor zone, South West Ethiopia, 2018.Methods: Community based comparative cross-sectional study was conducted from May to July, 2018 among 584(urban 292 and rural 292) married women of reproductive age group. The data were entered into EPI data version 3.1 and exported to SPSS version 20 computer software for analysis. Both Bivariate and multivariable logistic regression analysis was used. Level of significance was declared at a p value of <0.05Results: A total of 288 in urban and 288 in rural married women were interviewed and yields a response rate of 98.6% both in urban and rural. Decision-making power in urban and rural was 55.2% [95% CI (52.7-64.6)] and 40.3% [95% CI (39.9-52.5)] respectively. In urban, being wives of government employed spouses [AOR 2.102 95% CI (1.16, 3.81)], knowledge on RH [AOR 3.33, 95% CI (1.20, 12.49)], above five years in marriage [AOR 1.91, 95% CI (1.19, 7.70)], were found to be predictors of women’s decision-making power.Conclusion and recommendation: Urban women had better power to make decisions than rural on reproductive health service utilization. The study revealed that in urban settings those women who had marriage duration five and more than five years, being wives of government employed spouses had more likely decision making power on reproductive health utilization but not in rural settings. Reproductive health interventions in the area should be promoted by considering empowering of married women on reproductive health service utilization.Article summary:Strength: the study was representative for urban and rural women on reproductive health service utilization.Limitation: the study is not without limitation.it has all limitation of cross-sectional studyIntroduction