Toxicity studies on chemicals registered under the European Union's Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation are provided as summaries instead of as a full study report. Because the registration data are used by regulatory agencies to identify chemicals of concern, the study summaries must accurately reflect the information in studies. A “study summary” should include sufficient information on the objectives, methods, results, and conclusions in the full study report in order for the relevance of the study to be determined. Sometimes a “robust study summary” is required, which should contain more detailed information to enable an independent assessment of the study. The aim of the present investigation is to examine how well published toxicity papers were reflected in study summaries submitted by registrants under REACH. Summaries of 20 published studies (peer‐reviewed studies, including 1 abstract) were examined and broad categories of various types of observed differences were derived. The extent to which information in the published studies was reported, as well as how accurately the information was reflected, varied. How accurately the information was reflected also varied. Differences between the published studies and the summaries included simple typing errors, unclear and incomplete reporting, as well as the omission of information on, for example, study design, results, or interpretation of the results, which in some cases could be considered relevant for the risk assessment. This raises concerns regarding the accuracy of study summaries and their use for decision making. Moreover, the possibility for third parties to independently assess and scrutinize the summaries is limited. Considering that we rely on REACH registration data for chemical safety, all data used for risk assessment should be accessible for thorough examination and fully independent assessment. Integr Environ Assess Manag 2019;00:000–000. © 2019 SETAC