Background: 0.6% of the population is transgender or gender diverse (TGD) and have a gender that differs from their sex assigned at birth (Flores et al., Williams Institute, 2016). TGD people face mistreatment and discrimination, and represent a vulnerable population which is understudied and not well-captured in large cohorts (James et al., National Center for Transgender Equality, 2015). Thus, little is known regarding their cancer risks, prevalence, and outcomes, particularly in the realm of hematologic malignancies. Efforts to study malignancy prevalence in TGD populations are of utmost importance to improve patient care. Limited data suggests TGD patients have higher rates of certain cancers, including lymphoma, compared to other patients, but require validation (Braun et al., Epidemiol Rev, 2017). To accomplish this goal, we sought to design and implement a reproducible data collection strategy to identify TGD patients within a cohort of patients with lymphoproliferative disorders at the Wilmot Cancer Center. Methods: We reviewed the charts of 2200 unselected, consecutive patients with any lymphoproliferative disorder from a single-center, regionally representative, database at the University of Rochester. Our algorithm included searching the following variables for suggestion of TGD identity: demographics, preferred name/alias, medications, problem list, medical/surgical history, social history, an electronic medical record (EMR) lesbian, gay, bisexual, and transgender (LGBT) tab, and karyotype data if available. Additionally, we searched each chart for the following terms: "transgender," "trans," "transsexual," "gender," "genderqueer," "non-binary," "non-conforming," "male to female," "MTF," "female to male," "FTM," "male," and "female" to identify TGD patients. Data on diagnosis, treatment, and more detailed demographics were collected for patients identified as TGD. We report descriptive analyses of our results. Results: Three transgender patients with lymphoproliferative disorders were identified, comprising 0.1% of the database (95% CI 0%, 0.4%). All were white, transgender women with diagnoses of follicular lymphoma, chronic lymphocytic leukemia, and atypical angiotrophic t-cell infiltrate concerning for lymphomatoid papulosis. All three were identified by medication history and searches for the terms "female" and "transgender" as well as aliases differing from legal name. Conclusions: More oncologic research must be done to explore the prevalence of specific malignancies in TGD populations. Such research is limited by inconsistent documentation of gender identity in EMRs resulting in lack of basic epidemiologic data on TGD people with cancer. Our chart review successfully identified three transgender patients. Among the methods used, medication histories, discrepancies between legal name and alias, and searches for the words "transgender" and "female" provided the most fruitful results. We expected diagnoses related to transgender identity, documentation of transgender identity, and the LGBT tab to yield significant results. However, these were low-yield sources in our study. Our inability to identify a percentage of TGD patients similar to prior data was likely multifactorial: 1) TGD patients may not want their gender identities known to oncologists and may not share related information; 2) oncologists may not ask about gender identity or related histories; and/or 3) TGD patients may seek care at outside institutions. Alternatively, the prevalence of lymphoma may be low in TGD populations, conflicting with prior data. Further research regarding TGD patients with hematologic malignancies necessitates specific collection of gender identity data within the EMR and large datasets such as the cooperative groups. More research is needed regarding the optimum questions regarding gender identity which will yield accurate data and maintain strong relationships between patients and providers. Disclosures Casulo: Celgene: Research Funding; Gilead: Honoraria, Other: Travel, accommodation, expenses; Roche: Other: Travel, accommodation, expenses.