Background Sex differences exist in the diagnosis and treatment of several cardiovascular diseases. Our objective was to determine whether sex differences exist in the use of guideline-recommended treatments in out-of-hospital cardiac arrest (OHCA). Methods We included adult patients with non-traumatic OHCA treated by emergency medical services (EMS) in the Resuscitation Outcomes Consortium Prehospital Resuscitation using an IMpedance valve and Early versus Delayed (ROC PRIMED) database during 2007–2009. Outcomes included prehospital treatment intervals, procedures, and medications. Data were analysed using multivariable linear and logistic regression models that adjusted for sex, age, witnessed arrest, public location, bystander cardiopulmonary resuscitation (CPR), and first known rhythm of ventricular tachycardia/fibrillation. Results We studied 15,584 patients; 64% were male and median age was 68 years (interquartile range 55–80). In multivariable analyses, intervals from EMS dispatch to first rhythm capture (p=0.001) and first EMS CPR (p=0.001) were longer in women than in men. Women were less likely to receive successful intravenous or intraosseous access (OR 0.78, 95% CI 0.71–0.86) but equally likely to receive a successful advanced airway (OR 0.94, 95% CI 0.86–1.02). Women were less likely to receive adrenaline (OR 0.81, 95% CI 0.74–0.88), atropine (OR 0.86, 95% CI 0.80–0.92), and lidocaine or amiodarone (OR 0.68, 95% CI 0.61–0.75). Conclusion Women were less likely than men to receive guideline-recommended treatments for OHCA. The reasons for these differences require further exploration, and EMS provider education and training should specifically address these sex differences in the treatment of OHCA.