['Recent data suggest that using vasopressin in combination with epinephrine (adrenaline) may improve treatment of out-of-hospital cardiac arrest. This study examined local experience with the combination of epinephrine and vasopressin administration.', 'Data were obtained from an urban, municipal emergency medical service that does not include vasopressin in its formulary. A physician is dispatched to the scene of all cardiac arrest patients treated by this system. Vasopressin could be administered in addition to epinephrine to subjects with out-of-hospital cardiac arrest by the on-scene physician. Demographic information, drug administration and return of pulses were abstracted from patient care records for a 1-year interval. Multivariate logistic regression was used to assess the relationship between vasopressin use and outcomes.', 'During the study period, data were available for 298 subjects receiving epinephrine-only (n=231, 78%), a combination of 40 IU vasopressin and epinephrine (n=37, 12%) or no vasopressor drugs (n=30, 10%). Among patients receiving vasopressor drugs, pulse was restored for 74 subjects (28%), and 56 subjects (21%) had a pulse on arrival at the hospital. Return of pulses was associated with witnessed collapse, bystander CPR, and an initial ECG rhythm of ventricular fibrillation or tachycardia. Subjects receiving vasopressin and epinephrine were more likely to have a return of pulses during the resuscitation (LR: 2.73; 95% CI: 1.24, 6.03) and at hospital arrival (3.85; 1.71, 8.65) than subjects treated with epinephrine alone.'] Is vasopressin administered with epinephrine associated with a return of a pulse in out-of-hospital cardiac arrest?