Aims/Background Seroma formation is the most common complication following breast surgery. However, there is little evidence on the readability of online patient education materials on this issue. This study aimed to assess the accessibility and readability of the relevant online information. Methods This systematic review of the literature identified 37 relevant websites for further analysis. The readability of each online article was assessed through using a range of readability formulae. Results The average Flesch-Reading Ease score for all patient education materials was 53.9 (± 21.9) and the average Flesch-Kincaid reading grade level was 7.32 (± 3.1), suggesting they were 'fairly difficult' to read and is higher than the recommended reading level. Conclusion Online patient education materials regarding post-surgery breast seroma are at a higher-than-recommended reading grade level for the public. Improvement would allow all patients, regardless of literacy level, to access such resources to aid decision-making around undergoing breast surgery.