Introduction: Atrial fibrillation (Afib) is a common cardiac manifestation of hyperthyroidism. The data regarding outcomes of A fib with and without hyperthyroidism are lacking. Hypothesis: We hypothesized that patients with Afib and hyperthyroidism have better clinical outcomes, compared with Afib patients without hyperthyroidism. Methods: We queried National Inpatient Sample database for years 2015 - 2017 using Validated International Classification of Diseases and Clinical Modification (ICD-10-CM) codes for atrial fibrillation and hyperthyroidism. Patients were separated into 2 groups- A fib with hyperthyroidism and A fib without hyperthyroidism. Results: Study was conducted on 68,095,278 pateints. A total of 9,727,295 Afib patients were identified, out of which 90,635(0.9%) had hyperthyroidism. The prevalence of hyperthyroidism was higher in patients with Afib (0.9% vs 0.4%, p value <0.001), compared with patients without A fib. Using multivariate regression analysis after adjusting for various confounding factors, the odds ratio of Afib with hyperthyroidism was 2.08 (CI 2.07 - 2.10 P<.0001). Afib patients with hyperthyroidism were younger, (70.9 vs75.1 years, p<0.0001) and more likely to be female (63.9% vs 47% p<0.0001) as compared with Afib patients without hyperthyroidism. Afib patients with hyperthyroidism had lower prevalence of CAD (36.4% vs 43.8%,p<0.0001), cardiomyopathy(24.1% vs 25.9%,p<0.0001), valvular disease (6.9% vs 7.4%,p<0.0001), hypertension(60.7% vs 64.4%,p<0.0001) , and diabetes mellitus (28.9% vs 31.8%,p<0.0001). Afib with hyperthyroidism group had lower all-cause mortality (3.3% vs 4.8%, p<0.0001), shorter mean length of stay (5.7 ±6.6 vs 5.9±6.6 days,p<0.0001) and hospitalization cost ($14968±21871 vs $15955±22233, p<0.0001). The disposition to home was higher in Afib with hyperthyroidism patients (50.6% vs 41.8 p<0.0001). Conclusions: Presence of hyperthyroidism is associated with Afib in both univariate and multivariate analysis. Afib patients with hyperthyroidism have better clinical outcomes, compared with Afib patients without hyperthyroidism.