Abstract Background Chimeric antigen receptor T-cell (CAR-T) therapies have changed the treatment landscape for various hematologic malignancies and are currently under development and being tested in clinical trials for multiple solid tumors. Given that patients commonly use the internet as a source of health-related information, we sought to investigate the quality, understandability, and readability of online information regarding CAR-T therapy. Methods We conducted a search in a commonly used search engine (Google) of five pre-determined search terms to identify 100 unique web pages regarding CAR-T therapy. Scientific publications were excluded. Validated instruments were used to ascertain health information quality (DISCERN), understandability (Patient Education Materials Assessment Tool; PEMAT), and readability (Flesch-Kincaid, Gunning Fog, and SMOG indices). Results were summarized using descriptive statistics. Results Among the 100 web pages reviewed, 68% originated from academic medical centers, and 64% included links to clinical trials. Only 11% of the web pages included references to primary literature. 17% of web pages were available in a language other than English, with Spanish (15%) and Arabic (7%) being the most common. Moderate-to-high quality information (DISCERN ≥ 3) was presented by 47% of web pages, and only 31% of web pages were considered understandable (PEMAT ≥ 70%). Average readability scores were 10.6 (SD = 2.09), 12.6 (SD = 2.3), and 13.1 (SD = 1.7) using the Flesch-Kincaid, Gunning Fog, and SMOG indices, respectively. Conclusion Our study highlights that online information for CAR-T therapies commonly features low-quality health information that is typically not understandable to the general population. Further, contrary to recommendations from federal agencies and medical societies, available online information requires, on average, high school reading comprehension. Healthcare teams and stakeholders should strive to improve existing content and ensure patients have access to trusted, high-quality information given the unique complexities, processes, and toxicities associated with receiving CAR-T therapy. Citation Format: Luis C. Garcia, Ana I. Velázquez. Quality and Accessibility of Online Information Regarding CAR-T Therapy in Hematologic Malignancies [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr B105.