Background The Netherlands and Belgium are among the top five worldwide of highest incidence in breast cancer, leading to an increase in post-mastectomy reconstruction interest. This study aims to analyze readability of Dutch-written online patient-directed information on breast reconstruction. Methods An online patient query for the term borstreconstructie was simulated using the largest search engine, Google. Content from the 10 most popular web sites from the Netherlands and Belgium was collected and formatted into plain text. Readability level assessment was performed using four available tools for the Dutch language: Accesibility.nl, Klinkende Taal, Texamen, and WizeNote, which measure readability according to the Common European Framework of Reference for Languages (CEFR). Results Of the 20 websites (10 Dutch and Belgian), breast reconstruction content was mainly written in B2/C1 and exceeded the recommended B1 level. The readability tool "Klinkende Taal" was found to have the lowest average CEFR level at B2 (average 4.01, 2.40-5.00), WizeNote (average 4.57, 3.00-5.00), and Accesibility.nl (average 4.58, 3.40-5.50). Both had a CEFR level B2/C1, while Texamen scored the highest average at C1 (average 4.77, 3.60-5.25). Kiesbeter.nl, a Dutch government web site, was found to comply with the recommended B1 level on their breast reconstruction information. Conclusions Readability of online health information on breast reconstruction was generally found to be too advanced for the lay population. Therefore, it may hold benefit for patient-directed health information to be analyzed and revised in order to tailor the information to the targeted population.