Background: Self-referral leads to diminished quality of health care service; increase resource depletion and poorer patient outcomes. However, significant number of patients referred themselves to the higher health care facilities without having referral sheet globally including Ethiopia. Even though the problem is much exacerbated in Ethiopia, there is limited evidence regarding to self-referral patients in Ethiopia in particular in the study area. Objective: To assess the magnitude and associated factors of self-referral among patients at adult outpatient department in Debre Tabor general hospital, North West Ethiopia. Method: Institution-based cross-sectional study was conducted from March 11-April 9, 2020 among 693 patients who attended adult outpatient departments. Systematic sampling technique was employed. Structured and pretested interviewer administered questionnaire was used for data collection. Data were coded, entered and cleaned in to Epi Info version 7.1 and exported to SPSS version 23 for further analysis. Binary logistic regression analysis was employed. In bivariable analysis p-value less than 0.25 was used to select candidate variables for multivariable analysis. P-value less than 0.05 and 95% confidence interval were used to select significant variables on the outcome of interest. Result: The proportion of self-referral was 63.9 % with 95% CI (60.5; 67.5). Formally educated, (AOR=1.83; (95% CI: 1.12, 3.01)), enrolled to Community Based Health Insurance (AOR=1.57; (95% CI: 1.03, 2.39)), poor knowledge about referral system (AOR=2.07; 95% CI: (1.28, 3.39)), not and partially available medication in the nearby Primary Health Care facilities (AOR=2.12; (95% CI: 1.82, 6.15)) & (AOR=3.24; (95% CI: 1.75, 5.97)) respectively and history of visiting general hospital (AOR=1.52; (95%CI: 1.03, 2.25)) were factors statistically associated with self-referral. Conclusion and recommendation: The proportion of self-referral was low compared to western Ethiopia. Socio demographic, individual and institutional factors were associated with self-referral. Therefore, regional health bureau better to work to fulfill the availability of medications in the primary health care facilities. In addition, Community Based Health Insurance (CBHI) agency should work to implement the law of out of pocket expenditure which states to pay 50% for self-referred patients who claim utilization of healthcare. Key words: Self-referral, referral system and Ethiopia