OBJECTIVES: To evaluate whether the provision of ACA has increased being up-to-date on colorectal cancer (CRC) screening (blood stool test, sigmoidoscopy, or colonoscopy) among age-eligible population with private insurance and to examine racial and ethnic disparities in the uptake of CRC screening METHODS:  This was a quasi-experimental study using data from the Medical Expenditure Panel Survey 2007-2014. We examined changes in the prevalence of being up-to-date on the CRC screening by race/ethnic groups between pre-ACA (2007 to 2010) and post-ACA (2011 to 2014). Our study population included nonelderly US adults aged 50 to 64 years with family income at 138% or more of the Federal Poverty Level (FPL) and private insurance plans. We included the uninsured as a comparison group not directly affected by the ACA.  RESULTS: Our study sample comprised 25,298 individuals, representing 303,358,483 US adults aged 50-64 years with private insurance (weighted n=169,187,558 in pre-ACA and 176,782,642 in post-ACA period). Overall prevalence of being up-to-date on the CRC screening increased from 59.8% in the pre-ACA to 63% in the post-ACA period (p=0.001). By race/ethnicity, we observed significant increases ranged from 3% among non-Hispanic (NH) whites (p=0.005) to 7.2% among Hispanics (p=0.001). However, using difference-in-differences analysis, we found that those changes in screening uptake were not associated with the provision of the ACA (i.e., elimination of the cost-sharing). Prevalence of being up-to-date was significantly lower among NH Asians, compared with NH whites in both Pre-and Post-ACA (44% vs. 61.4%, p<0.0001 in the pre-ACA and 48.5% vs. 64.5%, p<0.0001, respectively). NH black had the highest prevalence (65.4%) followed by NH whites, others (56.6%), and Hispanic (55.5%) in the post-ACA (p<0.0001). CONCLUSIONS: Although the prevalence of being up-to-date on CRC screening among age-eligible US population increased slightly after the implementation of the ACA, the ACA has not reduced racial and ethnic disparities in screening uptake.