Patient education is a critical component of effective medical care; > 50% of patients seek medical information from online sources. The recommended reading level is sixth grade. This study examines reading level of current online educational resources for patients with pheochromocytoma. A review of 50 online patient educational materials related to pheochromocytomas was performed. Using three validated instruments: Flesch Reading Ease (FRE), Simplified Measure of Gobbledygook (SMOG), and Gunning Fog Index (GFI) scores, the reading grade level was calculated, and Spearman correlations were performed to evaluate associations between the reading instruments. Thirty-two online patient educational materials were included. The majority of the materials were from academic and research institutions (47%), followed by general information and overviews (19%), government health resources (9%), cancer-specific organizations (9%), support and advocacy groups (9%), and children's health (6%). There were no patient materials that were written at the appropriate grade level. Materials were above a twelfth-grade reading level in 61% of sources (FRE = 78.2%, SMOG = 40.6%, GFI = 59.4%). There were strong, positive correlations between the three reading instruments utilized in the analysis. Readable educational materials facilitate effective healthcare literacy and empower patients to participate in health care decisions, which is especially important given the complex diagnostic and therapeutic considerations for pheochromocytomas. This study is the first to assess readability of online educational resources for patients with pheochromocytoma and reveals a significant gap in the availability of materials that meet the recommended grade level. Developing online education materials that meet the recommended reading grade level is essential to inform patient education and shared decision-making.