Purpose Frailty is a clinically relevant syndrome characterized by a decline in reserve across multiple physiological systems. Frailty is associated with high mortality in patients undergoing ventricular assist device (VAD) implant and in patients referred for heart transplantation (HTx). The relative impact of frailty on outcomes in VAD and HTx patients remains unknown. Methods 72 HTx and 44 VAD recipients (2015-2017) had frailty testing prior to surgery. The 5-domain Fried score was used to classify frailty: unintentional weight loss, exhaustion, weak grip strength, slow gait speed, and low physical activity. Patients were frail if they met ≥ 3 domains, and pre-frail if they met 1-2 domains. We used the Cox proportional hazards model to assess the association between frailty, and each individual domain, with 1-year mortality. We evaluated the relationship between frailty status and mortality for HTx and VAD patients collectively, but evaluated the relationship between each frailty domain and mortality for HTx and VAD patients separately. We used linear regression to assess the association between frailty and the length of hospital stay post-intervention. Results HTx (n=72) and VAD (n=44) patients (82% men, age 52.5±11, BMI 26±5.1, 21.4% HTN, 21.4% DBM, 21.4% ICM) underwent frailty testing; 43% were frail. Mean follow-up was 273 days. Frailty was not significantly associated with 1-year mortality (HR 2.6, 95% CI 0.9-7.6, p=0.08). Low grip strength was the only domain significantly associated with mortality (HR 3.3, 95%CI 1.2-9.3, p=0.023) with an increased mortality in patients undergoing VAD implant (60% mortality vs. 9% in frail and non-frail grip strength, p<0.001). However, mortality was not significantly different for HTx patients with frail or non-frail grip strength (11% vs. 13% in frail and non-frail grip strength, p=1.0). Length of hospital stay (LOS) was significantly associated with frailty; average LOS was 34.2 days (95% CI 9-59) longer for frail patients (p=0.008). Conclusion We observed a significant association between weak grip strength and mortality, as well as between frailty and LOS. However, our study lacked adequate statistical power to determine an association with mortality. Our study generates the hypothesis that frail grip strength may be more concerning for mortality in VAD than in HTx recipients.