Background: Out of pocket expenditure at the point of health service delivery increases thernlikelihood of catastrophic financial expenditures for health service users. In Ethiopia, aroundrn33.7% of total health expenditure comes from the household out-of-pocket expenditure. Suchrnsignificant out of -pocket payment creates financial barriers to access to health services and putsrnpeople at risk of poverty. Therefore, this finding offers new evidence on the magnitude andrndeterminants of out of pocket expenditure on out-patient care. rnObjectives: To investigate the magnitude and determinants of Out-of-Pocket medical expenditurernamong outpatients visiting Hospitals in East Shoa Zone, Oromia, Ethiopia. rnMethods: An institution based cross-sectional study was conducted on 422 participants visitedrnpublic hospitals in East Shoa zone from February 18 to Murch 9, 2019. Data collection took placernthrough interviews with patients coming to the outpatient pharmacy after finishing their visits atrnthe different outpatient departments in the hospitals. Data were collected via structured questioner,rnthen it was cleaned, coded, entered into EPI info 7 and exported to SPSS version 23 statisticalrnpackage for analysis. Descriptive statistics and both bivariate and multivariable logistic regressionrnwere used to identify determinants of OOP. The existence of association was measured using oddsrnratio with 95% confidence intervals. rnResults: From the 378 interviews included in the final analysis, the proportion of participants paidrnout-of-pocket medical expenditure was 332(87.8%) and the mean out-of-pocket medicalrnexpenditure was 351.48 ETB (12.55USD) per visit, while the direct medical cost was 132.86 ETB.rnIn addition, the study identifies some significant determinants for the out-of-pocket medicalrnexpenses of OPD services namely, residence, education of the household head and sex of thernhouseholds. rnConclusion: - Most of the study participants were pay OOPME with the high average for OPDrnservice received which is high when compared with the mean monthly household per capitarnincome and OOPME found to determine by residence, educational level of household head andrnsex of the household. Health managers should focus on the implementation of CBHI and start SHIrnin order to protect society from financial risk that occurred at the service delivery.