9033 Background: Although H/O topics are essential for primary care physicians, internists and subspecialists, the H/O curriculum is not standardized across IM residency programs. We aimed to identify the most important H/O topics for IM residents to learn, according to IM generalists and H/O specialists. Methods: We used a modified Delphi approach to conduct a 2-round cross-sectional survey of IM generalists and H/O specialists at the University of California, San Francisco and Stanford University. Participants rated the importance of H/O curricular topics gathered from national H/O and IM organizations on a 1-5 scale (very unimportant to very important). Participants then viewed their own ratings compared to the group mean and standard deviation (SD) for each topic from round 1 and could change their ratings in round 2 if they wished. We used a content validity index (CVI, the percentage of respondents who rated the topic ≥4) of >75% to identify the most important topics. We compared the effect sizes of the differences between mean generalist and specialist ratings for each topic using Cohen’s d. Results: The survey included 239 topics (75 classical hematology, 52 malignant hematology, 112 solid oncology). The round 1 survey was sent to 132 clinicians (68 generalists, 64 H/O specialists), with 92 round 1 responses (response rate [RR] 69.7%) and 77 round 2 responses (RR 83.7%). The average variance decreased from round 1 to round 2 (1.00 to 0.86), indicating increasing agreement. Ninety-two topics met the CVI threshold: 41 from classical hematology, 15 from malignant hematology, and 36 from solid oncology. The Table shows the highest rated topics as examples. Most effect sizes were small (58.6%), indicating agreement between generalists and specialists across most topics. Conclusions: With input from both generalists and H/O specialists, we identified the most important H/O topics for IM residents, which can guide curriculum development for IM residency programs. [Table: see text]