BACKGROUND: We examined all-cause mortality and long-term thromboembolic risk (ischemic stroke, transient ischemic attack, systemic thromboembolism) in patients with and without familial atrial fibrillation (AF). METHODS AND RESULTS: Using Danish nationwide registry data, we identified all patients diagnosed with AF (1995-2012) and divided them into those with familial AF (having a first-degree family member with a prior AF admission) and those with nonfamilial AF. We paired those with and without familial AF according to age, year of AF diagnosis, and sex in a 1:1 match. Using cumulative incidence and multivariable Cox models, we examined the risk of long-term outcomes. We identified 8658 AF patients (4329 matched pairs) with and without familial AF. The median age was 50 years (interquartile range 43-54 years), and 21.4% were women. Compared with nonfamilial AF patients, those with familial AF had slightly less comorbid illness but similar overall CHA2DS2-VASc score (P=0.155). Median follow-up was 3.4 years (interquartile range 1.5-6.5 years). Patients with familial AF had risk of death and thromboembolism similar to those with nonfamilial AF (adjusted hazard ratio 0.91 [95% CI 0.79-1.04] for death and 0.90 [95% CI 0.71-1.14] for thromboembolism). CONCLUSIONS: Although family history of AF is associated with increased likelihood for development of AF, once AF developed, long-term risks of death and thromboembolic complications were similar in familial and nonfamilial AF patients.