Background: Smoking cessation after a cancer diagnosis improves cancer outcomes. Therefore, it is important for cancer centers to provide educational resources to encourage patients to quit smoking. The NIH recommends that patient reading materials be written at a grade 6-7 reading level to maximize comprehension. As smokers on average have lower educational attainment than the general population, they may have particular difficulty comprehending smoking cessation materials written at advanced grade levels. Methods: This study evaluated the reading level of online resources via textual analysis of smoking cessation webpages associated with 63 NCI-Designated Cancer Centers or their affiliated medical centers or universities. Reading level was assessed using the WebFx Readability Test Tool. Differences in grade level were calculated by Mood’s Median Test. Content was evaluated for the quality of information, including textual analysis of print-out pamphlets. Non-English content and ease of navigation to webpages was documented. Results: Availability: Of 63 cancer centers, 42 (67%) had smoking cessation webpages. Among centers that did not have their own webpages, 14 had smoking cessation webpages hosted by affiliated medical centers and the remaining 7 had webpages hosted by affiliated universities. Reading Level: The median grade level for online smoking cessation materials was 9 (interquartile range IQR 8-10). There was no significant difference in grade level based on cancer center region, ranking, or whether the webpage was hosted by the cancer center, medical center or university. 17 webpages (27%) had print out pamphlets available, which had a median reading level of 8.5 (IQR 7-10). Information Quality: 27 webpages (43%) explicitly stated that smoking cessation improves cancer outcomes, 15 (24%) included details about smoking cessation medications, 16 (25%) provided information on behavioral counseling, and 14 (22%) described the risks/benefits of e-cigarette use. Only 4 (6%) had information on all four topics, while 21 (33%) did not have information on any of these four topics. Accessibility: Only 3 webpages (5%) were available in multiple languages. 12 webpages (19%) were inaccessible by search from the homepage with common terms (i.e. smoking, quit smoking, tobacco, etc). 38 webpages (60%) required 3 or more clicks to reach from the center homepage. Conclusions: Online smoking cessation materials at leading cancer centers exceed recommended reading levels, which can inhibit comprehension for patients trying to quit smoking. These webpages do not routinely include information on cancer outcomes or on evidence-based medications and behavioral change interventions to assist patients in quitting. Given the survival benefit found in cancer patients who quit smoking, it is imperative that educational materials from cancer centers maximize comprehension and accessibility.