BackgroundTrustworthy educational information for patients is critical for increasing their knowledge base and preparing them for shared decision making with clinicians. As the internet has become an important source of health information for many patients, the purpose of this study was to assess the quality and content of websites with educational content about immune checkpoint inhibitors.MethodsWe performed an environmental scan of the currently available websites providing educational information for patients about immune checkpoint inhibitors. We used three search engines: Google, Bing, and Yahoo! (9/20/2021). Two independent investigators selected relevant uniform resource locators (URLs), appraised the quality of the websites, and collected their characteristics. We evaluated the accuracy, completeness, technical elements, design and aesthetics, readability, usability, and accessibility of the websites. The user experience was also evaluated.ResultsWe identified 37 websites for analysis. In 10 websites (27%), it was not possible to know the source of the information provided. Thirty-three (89%) provided a definition with a simple explanation of cancer and treatment and 30 (81%) on complications of immune checkpoint inhibitors; only seven (19%) provided information about the balance between risks and benefits. Thirty-five (95%) provided a statement of purpose. Regarding the design, all 37 (100%) had appropriate visual aspects, typography, and grammar. Thirty-six (97%) were well organized. For most of the websites (n = 35, 95%) the content was easy to find. Only two websites had a readability score of 6, while the others had higher scores. Regarding the user experience, the overall quality of websites was rated as excellent in 16 (43%), good in 14 (38%), and fair in 7 (19%).ConclusionsOur findings reveal that websites with information about immune checkpoint inhibitors mostly have general information about cancer, the treatments, and adverse events. Few websites provide information about the balance between harms and benefits of treatment, costs, the source of the information, or the hierarchy of evidence. These findings identify the gap in the quality and content of websites for patients treated with immune checkpoint inhibitors and can help website creators and developers.