Background: Although the risks of adverse pregnancy outcomes associated with anti-Drnantibodies are reduced after the implementation of immunization to the D antigen, itâ€™s still arnconcern for most Sub-Saharan African countries, where there is poor and sometimes nornAlloimmunization prevention following potentially sensitizing events. This may result in therncompromise of the womanâ€™s obstetric care and increase perinatal morbidity and mortality. InrnEthiopia the weight of the problem is less known and there is no study done in the study area.rnThis study intended to fill this knowledge gap.rnObjective: To study prevalence and determinant of Rh Alloimmunization in Rh negative rnmother in three teaching hospitals (TAH, GMH and ZMH) Addis Ababa, Ethiopia. rnMethods and Materials: Hospital based cross-sectional study was conducted from 328 Rhrnnegative pregnant women who booked for antenatal and delivery service utilization in TASH,rnGMH and ZMH from October 2020 to May 2021 to assess prevalence and determinant of RhrnAlloimmunization in Rh negative women. The data were collected by means of structuredrnquestionnaires. The data were entered, coded and analyzed using Statistical Package for SocialrnScience (SPSS) version 25. Descriptive and logistic regression analyses were conducted.rnStatistical tests were done at a level of odds ratio with 95% confidence intervals and significancernof p < 0.05. Variables with P value < 0.25 during the bivariate analysis were included in thernmultivariate analysis to see the effect of confounding factors rnResults and conclusion: The study revealed that prevalence of Rh D negative and RhrnAlloimmunization in the study area were 2.1% and 17.1% respectively. Being unemployed, notrnusing prophylaxisâ€™s anti-D, having previous sensitizing event and having two or more pregnancyrnwere statistically significant with Rh alloimmunized (p