<h3>Purpose</h3> The purpose of this study was to investigate the impact of weight change in waitlisted candidates on posttransplant outcomes following orthotopic heart transplantation (OHT). <h3>Methods</h3> The UNOS database was queried to identify adult (≥18 years) patients undergoing isolated, primary OHT from 1/1/2010 to 3/20/2020. Percent weight change was calculated from time of waitlisting to OHT, and patients were stratified into 3 cohorts based on weight change. The primary outcome was one-year survival among cohorts, and multivariable Cox Proportional Hazards modeling was used for risk-adjustment, including adjustment for time spent on waitlist. A secondary analysis was conducted to compare outcomes of recipients waitlisted ≥90 days. <h3>Results</h3> 57,107 patients were included, 48,299 (84.6%) with stable weight, 2,927 (5.1%) with ≥5% weight loss, and 5,881 (10.3%) with ≥5% weight gain. Median age was similar across cohorts with predominantly white recipients with non-ischemic cardiomyopathy. Waitlist time was longest in patients with weight gain and shortest in those with stable weight (417 vs 74 days, P<0.001). Patients with weight loss had higher rates of dialysis dependency, pacemaker, and drug-treated acute rejection at one year (all P<0.05). Ninety-day and one-year posttransplant survival was lowest in the weight loss (Figure). Multivariable modeling identified both ≥5% weight loss (HR 1.26, 95% CI 1.07-1.48) and decreasing weight (per 1%, HR 1.02, 95% CI 1.01-1.03) as risk-adjusted predictors of one-year mortality. In sub-analysis of OHT recipients waitlisted ≥90 days, ≥5% weight loss (HR 1.33, 95% CI 1.11-1.61) and decreasing weight (per 1%, HR 1.02, 95% CI 1.01-1.03) remained significant predictors of one-year mortality. <h3>Conclusion</h3> OHT recipients with ≥5% weight loss while on the waitlist comprise a small, but higher risk population with increased rates of postoperative complications and decreased survival. Efforts focused on nutritional optimization and preventing weight loss while awaiting OHT appear warranted.