Background: There is increasing use of online word of mouth opinion (user feedback) systems for general services but its use in online learning has not been previously investigated. Aim: To understand why users of BMJ Learning provide and read word of mouth feedback, and whether this feedback influences uptake of modules by prospective users. Method: Online questionnaire of users of BMJ Learning who had completed online user feedback. Result: 109 questionnaires were completed (response rate 25). The main motivation to contribute was to influence the authors of the module (66), and 43 stated that they wanted to help other users to make an informed choice. 16 stated that they wanted to develop an online community of learners. The main motivation to read the user feedback was to see if they agreed with the comments (56). Conclusion: Online word of mouth opinion (user feedback) appears to be useful for online learners. There are also system design considerations since the attempt to create an online community of learners that is desired by some users will not be appreciated by others. Further research with a larger number of users is recommended to confirm the findings.