ObjectiveThis study aimed at assessing clients’ satisfaction and associated factors among adults. A cross sectional facility based study was conducted on 420 clients of Yekatit 12 Hospital Medical College from 1 June 2016 to 1 July 2016. Data was entered, cleaned, and analyzed using SPSS statistical package. Data was analyzed using a multivariable logistic regression model to find out the most significant predictors for clients satisfaction with outpatient services at Yekatit 12 Hospital Medical College.ResultsThis study showed that the overall clients’ satisfaction level towards out-patient health service at Yekatit 12 Hospital Medical College was 47% at 95% CI (42.5, 51.7%). The most frequently identified problems were: lack of clean toilet in nearby the waiting areas, lack of waiting area particularly at pharmacy, inadequate furniture like chair, lack of adequate drugs and supplies, lack of privacy at the examination room, lack of direction signs, and poor communication between clients and health service providers. In conclusion the overall satisfaction level of the patients is low, so this demands the Hospital to take further action on the identified problems to improve the services delivered to the patients.Electronic supplementary materialThe online version of this article (10.1186/s13104-018-3603-3) contains supplementary material, which is available to authorized users.