Background: This study investigated the impact of weight change in waitlisted candidates on posttransplant outcomes following orthotopic heart transplantation (OHT). Methods: The United Network for Organ Sharing database was queried to identify adult patients undergoing isolated, primary OHT from 1/1/2010 to 3/20/2020. Patients were stratified into 3 cohorts based on percent weight change from listing to OHT. The primary outcome was one-year survival, and multivariable modeling was used for risk-adjustment. A secondary analysis compared outcomes of recipients waitlisted ≥90 days. Results: A total of 22,360 patients were included, 18,826 (84.2%) with stable weight, 1,672 (7.5%) with ≥5% weight loss, and 1,862 (8.3%) with ≥5% weight gain. Median age was similar across cohorts. Waitlist time was longest in patients with weight gain and shortest in those with stable weight (417 vs 74 days, P<0.001). The weight loss cohort 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 cohort. 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 recipients waitlisted ≥90 days, ≥5% weight loss and decreasing weight remained significant independent predictors for mortality. Conclusion: Waitlisted OHT candidates with ≥5% weight loss comprised 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.