['The Joint Commission began certifying primary stroke centers (PSCs) in December 2003 and provides a standardized definition of stroke center care. It is unknown if PSCs outperform noncertified hospitals. We hypothesized that PSCs would use more recombinant tissue plasminogen activator (rt-PA) for ischemic stroke than would non-PSCs.', 'Data were obtained from the Nationwide Inpatient Sample from 2004 to 2009. The analysis was limited to states that publicly reported hospital identity. All patients ≥18 years with a primary diagnosis of acute ischemic stroke were included. Subjects were excluded if the treating hospital was not identified, if it was not possible to determine the temporal relationship between certification and admission, and/or if admitted as a transfer. Rt-PA was defined by ICD9 procedure code 99.10. All eligibility criteria were met by 323 228 discharges from 26 states. There were 63 145 (19.5%) at certified PSCs. Intravenous rt-PA was administered to 3.1% overall: 2.2% at non-PSCs and 6.7% at PSCs. Between 2004 and 2009, rt-PA administration increased from 1.4% to 3.3% at non-PSCs and from 6.0% to 7.6% at PSCs. In a multivariable model incorporating year, age, sex, race, insurance, income, comorbidities, DRG-based disease severity, and hospital characteristics, evaluation at a PSC was significantly associated with rt-PA utilization (OR, 1.87; 95% CI, 1.61 to 2.16).'] Do joint commission primary stroke centers utilize more rt-PA in the nationwide inpatient sample?