Abstract Introduction: Disparities in healthcare reflect varying access to quality care, and the reception of quality care increases survival. Multiple factors can contribute to disparities in health care. Although the Affordable Care Act (ACA) offered the health disparities reduction by promoting access to equitable and more efficient health care, however there is still a wide gap in healthcare access, quality, and outcomes. One important factor is the lack of Medicaid expansion (ME) in all states of the US. In this study, the effect of ME is compared in California and Florida, the states with and without ME respectively, by looking into hysterectomy procedures (HP) done in these two states. Methods: We used 2009 and 2011 Florida and California State Inpatient Database (SID) of the Healthcare Cost and Utilization Project (HCUP). Our included population (n=3,043,460) were female portion of the database. The outcome variable was hysterectomy identified by ICD-9 codes. Patient-level factors including race/ethnicity, age, insurance type, income level, and other comorbidities were analyzed as explanatory variables. Logistic regression analyses were used to identify independent predictors of hysterectomy. Statistical analysis was conducted using SAS Version 9.4. Results: Among the Florida subjects, highest rate of HP is observed in Caucasian women (57.26%) followed by black women (21.85%). Also, the likelihood of HP is increased in women who are age 36-45 (39.83%) followed by age 46-55 (34.95%), and belong to the 1st and 2nd income levels (49.51%). Among the California subjects, highest rate of HP is in Caucasian women (52.35%) followed by Hispanics (29.09%), and women age 46-55 (39.69%) followed by age 36-45 (36.31%), and belong to 2nd and 3rd income levels (51.13%). Logistic regression analysis demonstrates that the odds of hysterectomy had a higher increase in Florida women in 2011 vs. 2009 (OR=1.238, 95% CI: 1.214-1.262), comparing to California (OR=1.124, 95% CI:1.107-1.141) respectively. Also, odds of HP had a higher increase among Florida women during 2011 Vs 2009 in comparison to that of California women. The increased odds were seen among the 2 lowest income levels, and insurance types. Conclusions: We found that likelihood of HP were seen more in Florida than California during years of 2009 and 2011. Also, we observed the reduction of likelihood of HP among California women during 2011 post-ACA when comparing to 2009, due to ME. However, the likelihood of HP was higher in Florida during 2011where the lack ME was a factor. Findings from this study highlights the importance of protective and preventable healthcare access for everyone regardless of races/ethnicities and other socio-economic factors, thus, brings better management of chronic diseases and improves women’s health at large. The provisions of important structures of ACA, such as Medicaid expansion, and health insurance exchange, in all states may reduce the health disparity among Medicaid holders, and self-pay patients. Citation Format: Zahra Bahrani-Mostafavi, Susan Rucker. The effect of ACA and Medicaid expansion on hysterectomy procedures among women in Florida and California [abstract]. In: Proceedings of the 15th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2022 Sep 16-19; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr C002.