Background: Hypertension is defined as two or more readings of systolic blood pressure measurement of 130 mm Hg or higher or diastolic blood pressure measurement of 80 mm Hg or higher. Undiagnosed hypertension is defined as individuals who were hypertensive but did not report having been told by a doctor that they have hypertension. Objective: This study aimed to assess the prevalence of undiagnosed hypertension and associated factors among bank workers in Bahir Dar city, Northwest Ethiopia 2020 Method: An institutional based cross-sectional study conducted in Bahir Dar city administration banks from February 24 to March 24 2020. Simple random sampling technique was used to select the study subjects. The data was collected through self-administered structured questionnaire and physical measurement. Logistic regression applied to assess the association between dependent and explanatory variables. The association interpreted using the odds ratio and 95% confidence interval. P-values less than or equal to 0.05 were considered statistically significant. Result- The prevalence of undiagnosed hypertension among bank workers was 24.8% with (95% CI 21.1 - 28.5). Age group 35-44 (AOR = 2.560, 95% CI: 1.603 - 4.088), being male (AOR = 3.606, 95% CI: 1.844 - 7.051), having moderate knowledge (AOR = 3.805, 95% CI: 2.285 - 6.338), having poor knowledge (AOR = 6.189, 95% CI: 3.069 - 12.479) and being physically in active (AOR = 2.914, 95% CI: 1.256 - 6.762) were significantly associated with undiagnosed hypertension. Conclusion- This study demonstrated the proportion of undiagnosed hypertension among bank workers is high. Age group of 35-44 years, being male, having moderate and poor knowledge and being physically inactive was significantly associated with undiagnosed hypertension. Therefore, there is an urgent need to create health awareness, frequent health screening and implementation of effective interventions targeting hypertension among this vulnerable group. Key words- Undiagnosed Hypertension, factors, bank workers, Bahir Dar, Ethiopia