Background: There are limited data on the extent of adolescent and young adult (AYA) education in pediatric and medical oncology fellowship programs. The purpose of this study was to assess the prevalence and content of AYA-focused training during pediatric and medical oncology fellowship and identify knowledge gaps for targeted educational curricular development. Methods: An anonymous, web-based survey for educators and trainees was developed, piloted and optimized by a study team comprising pediatric and adult oncologists. The survey contained questions on respondent demographics, AYA curriculum, provider comfort in managing specific AYA care domains, and priorities for future AYA educational content. In October 2021, email invitations containing the survey link were sent to program directors (PDs) and associate program directors (APDs) at 251 hematology/oncology fellowship programs (with 119 pediatric and 178 adult PDs/APDs) identified through the American Medical Association’s Fellowship and Residency Electronic Interactive Database Access. PDs were asked to participate and also distribute the survey to current fellows. The survey remained open for 3 months. Fisher’s exact test was used to assess for associations between discrete variables including amount of current education vs level of importance and demographic groups. Results: Respondents represented 69 programs (27%). There were 130 respondents who completed curriculum and demographic questions and 112 who completed detailed topic questions. Respondents comprised 51 PDs/APDs (32 pediatric and 19 adult) and 58 fellows (33 pediatric and 25 adult). 85% of PDs (44/51) do not have a formal AYA curriculum. Of these, 80% (35/44) offer some topic-specific lectures, while 20% (9/44) provide little/no education in any topics. For nearly all topics, at least 45% of respondents reported little/no education. Although onco-fertility and survivorship are the most frequently taught topics, 36% and 42% of respondents, respectively, reported little/no education in these areas. Substance abuse is least commonly taught. Both PDs and fellows believe that AYA topics are more important for inclusion in future curricula despite how infrequently they are currently taught (very/extremely important for inclusion vs moderate/great deal of current amount of education, p = 0.0001 for all topics). Overall, respondents indicated the most important topics for inclusion in fellowship curriculum were onco-fertility (82%), survivorship (78%), and communication (77%). Conclusions: These data highlight the large gap in hematology/oncology fellowship education in AYA topics and a paucity of formal educational curricula. Efforts are needed to provide both medical and pediatric oncology fellows with the knowledge and skills required to provide optimal care for AYAs.