BACKGROUND To date, no studies evaluated implicit bias among clinicians caring for children with advanced heart failure. OBJECTIVES This study aims to evaluate implicit racial and socioeconomic bias among pediatric heart transplant clinicians. METHODS A cross-sectional survey of transplant clinicians from the Pediatric Heart Transplant Society was conducted between June and August 2021. The survey consisted of demographic questions along with explicit and validated race and socioeconomic status (SES) implicit association tests (IATs). Implicit and explicit biases among survey group members were studied and associations were tested between implicit and explicit measures.RESULTS Of 500 members, 91 (18.2%) individuals completed the race IAT and 70 (14%) completed the SES IAT. Race IAT scores indicated moderate levels of implicit bias (mean = 0.33, d = 0.76; P < 0.001; ie, preference for White in-dividuals). SES IAT scores indicated strong implicit bias (mean = 0.52, d =1.53; P < 0.001; ie, preference for people from upper SES). There were weak levels of explicit race and wealth bias. There was a strong level of explicit education bias (mean = 5.22, d = 1.19; P < 0.001; ie, preference for educated people). There were nonsignificant correlations between the race and the SES IAT and explicit measures (P > 0.05 for all). CONCLUSIONS As observed across other health care disciplines, among a group of pediatric heart transplant clinicians, there is an implicit preference for individuals who are White and from higher SES, and an explicit preference for educated people. Future studies should evaluate how implicit biases affect clinician behavior and assess the impact of efforts to reduce such biases. (J Am Coll Cardiol HF 2023;11:19-26)& COPY; 2023 by the American College of Cardiology Foundation.