Background There are limited data on the sex-based differences in the outcome of readmission after cardiac arrest. Methods and Results Using the Nationwide Readmissions Database, we analyzed patients hospitalized with cardiac arrest between 2010 and 2015. Based on () codes, we identified comorbidities, therapeutic interventions, and outcomes. Multivariable logistic regression was performed to assess the independent association between sex and outcomes. Of 835 894 patients, 44.4% (n=371 455) were women, of whom 80.7% presented with pulseless electrical activity (PEA)/asystole. Women primarily presented with PEA/asystole (80.7% versus 72.4%) and had a greater comorbidity burden than men, as assessed using the Elixhauser Comorbidity Score. Thirty-day readmission rates were higher in women than men in both PEA/asystole (20.8% versus 19.6%) and ventricular tachycardia/ventricular fibrillation arrests (19.4% versus 17.1%). Among ventricular tachycardia/ventricular fibrillation arrest survivors, women were more likely than men to be readmitted because of noncardiac causes, predominantly infectious, respiratory, and gastrointestinal illnesses. Among PEA/asystole survivors, women were at higher risk for all-cause (adjusted odds ratio [aOR], 1.07; [95% CI, 1.03-1.11]), cardiac-cause (aOR, 1.15; [95% CI, 1.06-1.25]), and noncardiac-cause (aOR, 1.13; [95% CI, 1.04-1.22]) readmission. During the index hospitalization, women were less likely than men to receive therapeutic procedures, including coronary angiography and targeted therapeutic management. While the crude case fatality rate was higher in women, in both ventricular tachycardia/ventricular fibrillation (51.8% versus 47.4%) and PEA/asystole (69.3% versus 68.5%) arrests, sex was not independently associated with increased crude case fatality after adjusting for differences in baseline characteristics. Conclusions Women are at increased risk of readmission following cardiac arrest, independent of comorbidities and therapeutic interventions.