The Affordable Care Act is expected to provide coverage for nearly 25 million previously uninsured individuals. Because the potential impact of the ACA on urological care remains unknown, we estimated the impact of insurance expansion on the use of inpatient urological surgeries using Massachusetts health care reform as a natural experiment.We identified nonelderly patients who underwent inpatient urological surgery from 2003 through 2010 using inpatient databases from Massachusetts and 2 control states. Using July 2007 as the transition point between pre-reform and post-reform periods, we performed a difference-in-differences analysis to estimate the effect of insurance expansion on overall and procedure specific rates of inpatient urological surgery. We also performed subgroup analyses according to race, income and insurance status.We identified 1.4 million surgeries performed during the study interval. We observed no change in the overall rate of inpatient urological surgery for the Massachusetts population as a whole. However, we saw an increase in the rate of inpatient urological surgery for nonwhite and low income patients. Our difference-in-differences analysis confirmed these results (all patients 1.0%, p=0.668; nonwhite patients 9.9%, p=0.006; low income patients 6.6%, p=0.041). At a procedure level insurance expansion caused increased rates of inpatient benign prostatic hyperplasia procedures but had no effect on rates of prostatectomy, cystectomy, nephrectomy, pyeloplasty or percutaneous nephrolithotomy.Insurance expansion in Massachusetts increased the overall rate of inpatient urological surgery only for nonwhite patients and low income patients. These data inform key stakeholders about the potential impact of national insurance expansion for a large segment of urological care.