Background: Contraception refers to the process of preventing pregnancy by inhibiting the reproductive and endocrine systems. Theassociation between combined oral contraceptive and hematological changes has been extensively researched, however, themagnitude of hematological changes has not been determined and factors associated with hematological changes have not beenadequately explored. Objective:To assess hematological profiles and associated factors among Combined Oral Contraceptive userchildbearing agewomen at Bahir Dar. Methods:An Institutional based comparative cross-sectional study was conducted at selected public health centers from February 18 to May 10/2026. A total of 198 women were enrolled using a consecutive sampling technique. Socio-demographic and clinical data were obtained via face-to-face interviews. Three milliliters of venous blood was collected from each study participants for complete blood count. The data were entered into EpiData version 4.7 and then exported to SPSS version 25 for analysis. Data comparisons between the two groups were conducted using the Mann-Whitney U-test. Bivariable and multivariable logistic regressions were performed to identify factors associated with hematological abnormality. P-values below 0.05 were considered statistical significant. Result: Hematocrit, hemoglobin level, platelet count, red blood cell count and lymphocyte percentage were significantly higher in combined oral contraceptive users compared to non-users. Hematological abnormalitywas 34.1% in users and 13.8% fornon-users.Among Users the magnitude of anemia, leukocytosis, leukopenia, thrombocytopenia and thrombocytosis in user in this study were 4.0%, 4.0%, 10.1, 0.0 and 26.3respectively. Age (35-49 years(AOR: 2.202:95%CI: 1.032-5.091, P = 0.031) and Long term use of combined oral contraceptives (≥ 5 years) (AOR: 3.071: 95% CI: 1.020-8.013, P = 0.030) were found to be significantly associated with hematological abnormality. Conclusion:This study concludes that combined oral contraceptive users had significantly higher hematocrit, hemoglobin level, platelet count, and red blood cell count and lymphocyte percentage. They also had higher magnitude of thrombocytosis and leukopeniain users.Older age and prolonged use of combined oral contraceptives were significantly associated with hematological abnormalities