Background: Data quality is a multi-dimensional term that includes accuracy, precision, completeness, timeliness, integrity, and confidentiality.The quality of data generated by a routine health information system is still very poor in low and middle-income countries.There is a paucity of studies as to what determines data quality in health facilities in the study area. Therefore, this study was aimed to assess the magnitude of the quality of routine health information system data and its determinants among health centers. OBJECTIVE:To assess data quality and its associated factors in routine health information system among health centers of West Gojjam Zone, Northwest Ethiopia in 2021. METHOD: A facilitybasedquantitative studydesign triangulated by qualitative method was conducted.A total of 314 health professionals from 32 health centers were selected using a simple random sampling procedure.Data were gathered and utilized using a standardized checklist, interviewer administered questionnaires, and key informant interviews guideline. Descriptive statistics to describe variables and binary logisticregression to identify factors associated with data qualitywere computed usingSTATA version 14. Variables withp-value of less than 0.25 in the bivariate analysis were entered in to multi-variablelogistic regression analysis. Then p-value of less than 0.05 at95%CIwas taken to declare statistically significant.Manual analysis was done forqualitative data collected from purposively selected key informants. Results:The study found level of good data quality practice 74% (95% CI: 68 - 78) at health center of West Gojjam Zone. Complexity of routine health information system format (AOR=3.8; 95%CI: 1.7-8.5), problem solving skillfor RHIS tasks (AOR=2.8; 95% CI: 1.2-6.4) and know duties, role and responsibilities (AOR=12; 95%CI: 5.6-25.8),were significantly associated with data quality and lack of human resource, poor feedback mechanisms, delay in completing data records, lack of use of data, inadequate training on health information systems were barriers affect data quality. Conclusions and recommendations: level of good data quality practice in the public health facilities was less than the expected national level. Complexity of routine health information system,problem solving skill for HIS tasks andknow duties, role and responsibilitieswere significantly associated with data quality.Training and written feedback should be provided to increase the knowledge and skills of the health workers. KEY WORDS: Data Quality; Routine Health Information System; West Gojjam