Abstract Disclosure: D. Toro-Tobon: None. H. Billings: None. I. Bancos: None. Background: Mentorship is crucial for training physicians' career development, yet evidence of its impact on endocrinology trainees is lacking. We assessed the current state of mentorship in endocrine fellowship training in the United States. Methods: We conducted a cross-sectional study between June and September 2023. Endocrine fellows were invited to complete an online questionnaire describing their mentorship experience and its influence on burnout, satisfaction, and scholarly productivity. Results: Of 153 participants (mean age 34, 69% women, 47% White, 20% Hispanic/Latino), 73% had a mentor. Having a mentor was not associated with age, gender identity, race, or ethnicity. Those without mentors were more commonly in two-year fellowships (63% vs. 81%, p=0.04), had less access to formal mentorship programs (48% vs. 21%, p<0.01), cited insufficient faculty availability for mentoring (11% vs. 26%, p=0.01), and encountered more challenges finding mentors in their training programs (11% vs. 38%, p<0.001). Mentored participants exhibited increased post-fellowship interest in academic practice (69% vs. 50%, p<0.01), higher involvement in clinical research (65% vs. 49%, p=0.01), more fellowship-dedicated scholarly time (36% vs. 22%, <0.001), a greater median number of publications (4.6 vs. 1.8, p<0.01) and abstracts (7 vs. 3.7, p<0.01), were more likely to have submitted a grant (29% vs. 5%, p=0.03) and had higher satisfaction with training (92% vs. 64%, p<0.001). Mentors were mostly chosen by mentees (70%) and shared gender identity (61%) but often had a different race or ethnicity (71.8%). The majority found mentorship relationships satisfactory (87%), contributing to increased academic productivity (84%) and reduced mentee burnout and stress levels (60%). In bivariate analysis, all mentor attributes significantly influenced higher academic productivity and mentee satisfaction. The most divergent for academic productivity were improved communication, alignment with expectations, inspiration for goal attainment, and effective networking. For mentorship satisfaction, distinctions were found in communication enhancement, goal-oriented assistance, knowledge/skill enrichment, and personalized career path development. Traits like active listening and adapting communication styles were not linked to decreased burnout, but actively supporting work-life balance independently correlated with reduced burnout. Conclusion: Mentorship positively affects endocrine fellows' scholarly productivity and career development. Yet, a significant number lack mentors or access to programs. Mentor attributes, like effective communication, goal alignment, and networking support boost productivity and satisfaction. However, reducing mentee burnout hinges on actively fostering work-life balance. Presentation: 6/3/2024