Introduction: Gasping has been found to be common after cardiac arrest and associated with increased survival to discharge for out-of-hospital cardiac arrests (OHCA). Active compression decompression (ACD) plus an impedance threshold device (ITD) improves brain blood flow and survival to hospital discharge with favorable neurologic function after OHCA compared with standard CPR (S-CPR). Hypothesis: We assessed the association of gasping during CPR on 1-year survival. Methods: The ResQTrial data, which compared ACD+ITD versus S-CPR, was used for these analyses. Nearly all one-year survivors had normal brain function. We included all evaluable subjects in the run-in and pivotal phases of the trial. Beginning in January 2007, the original case report forms were modified to include whether or not spontaneous gasping or breathing was observed at any time during CPR. A logistic regression analysis was performed. Odds ratios (OR) were adjusted for ResQTrial study intervention arm, pre-specified prognostic factors, and study site, and were expressed for 1 standard deviation increment in patient age, total CPR duration, and epinephrine dosage. P-values < 0.05 were considered statistically significant. Results: Overall, 1879 subjects were included with data available on gasping status. Gasping was reported in 87/910 (9.6%) subjects in the S-CPR group vs. 116/969 (12.0%) in the ACD+ITD CPR group (p=0.09). In the combined cohort, one-year survival was significantly increased in patients with gasping during CPR 44/203 (22%) vs. 78/1676 (5%), p<0.001. In multivariable analysis, gasping during CPR was associated with a 3.49 (95% CI: 1.98-6.15) adjusted OR of 1-year survival. Other factors significantly associated with 1-year survival were: ventricular fibrillation as first recorded rhythm 13.28 (6.61-26.67), pulmonary edema 2.38 (1.16-4.92), age 0.56 (0.43-0.72), total CPR duration 0.28 (0.18-0.44), and epinephrine dosage 0.49 (0.30-0.82). Conclusions: Gasping during CPR is associated with a higher likelihood of one year survival after cardiac arrest. These new findings demonstrate the importance of recognizing gasping during CPR and provide a rationale for not terminating CPR prematurely in patients with ongoing gasping efforts.