Background: The Affordable Care Act (ACA) expanded Medicaid coverage in 2010. It is unknown what impact the ACA expansion has had on a timely diagnosis for patients with melanoma. We hypothesize Medicaid ACA expansion has decreased the odds of being diagnosed with Stage IV melanoma. Methods: The National Cancer Database was queried. Analysis was restricted to patients diagnosed (dx’d) in or after 2010. Stage IV dx was the outcome variable. Predictors were dx’d at an already expanded ACA state (ES) or not (NES). Covariates were age, race, sex, education status, income, rural setting, and Charlson co-morbidity index. Univariate and Multivariate analyses were performed using logistic regression (table). The outcome model was adjusted using a generated Propensity Score as a continuous variable. An interaction term was used to evaluate for effect modification of ES on the association between race and Stage IV. Results: 219,475 patients diagnosed in 2010 or later were included. Median age was 62 years. By Univariate analysis, NES, age > = 65, black race, male sex, lower educational and income level, rural area, and a higher Charlson score were significantly associated with increased odds of being dx’d with Stage IV melanoma (all p < 0.001). By Multivariate Analysis, these associations persisted except for rural area and age. After adjusting for propensity score, ES patients were 9% less likely to be diagnosed with Stage IV melanoma as compared with NES patients (OR = 0.91 p < 0.001; 95% CI 0.867 – 0.959). ACA expansion status was an effect modifier on the association between race and late diagnosis (p = 0.004 for interaction term). For NES patients, black race had 3.26 odds (p < 0.001 95% CI 2.56 – 4.18) of being diagnosed with Stage IV as compared with white patients. The odds dropped to 1.76 (p 0.004; 95% CI 1.20 – 2.57) for ES patients. Conclusions: ES patients were less likely to be diagnosed with Stage IV melanoma as compared to NES patients. Medicaid expansion decreased the likelihood for black patients to be diagnosed with Stage IV as compared with whites. This suggests Medicaid expansion improves access to care and earlier diagnosis of melanoma and decreases racial gaps.