ABSTRACT Illegal material is increasingly appearing on popular mainstream websites. Many commentators worry about the impact of such material on adolescents' psycho-sexual development and the potential for some legal pornography to act as a gateway to child sexual exploitation material for users of any age. In this study, we collected publicly available data from a popular legal pornography website to assess the risk of adolescent exposure to content that may hinder healthy psycho-sexual development. We analysed over 27 million customer searches involving 149 video tags from this site. Five international experts on the effects of pornography rated the tags, categorising them into five overlapping genres: mainstream, incestuous, underage, aggressive and non-consensual. They also assessed the potential risk each genre posed. Our analysis found a significant positive correlation between the harm ratings and the frequency of tags used as search terms. Additionally, eleven of the twelve tags with the highest mean risk scores involved potential underage and/or incestuous content. This study highlights a concerning relationship between the harm ratings of various pornographic genres and their popularity as search terms. While exploratory, these results emphasise the need for regulatory measures to address the presence of harmful material on mainstream websites. PRACTICE IMPACT STATEMENT The study has practical implications for the regulation of potentially harmful pornography by legal pornography sites. The sites should (a) control the use of tags and how new tags are developed in order to prevent content creators from advertising potentially illegal material, (b) vet all content before it is uploaded for public consumption, and (c) implement screening systems to retrospectively find and eradicate all illegal or harmful content already in their collection.