With their broad scope, high publishing volume, a peer review process based on the scientific soundness of the content, and an open access model, mega journals have become an important part of scholarly publishing. The main aim of this paper is to determine the most important factor that influenced researchers' decisions to submit their academic work to these type of journal. To this end, an online survey has been disseminated from November 2016 to August 2017, targeting the corresponding authors of the European Scientific Journal, ESJ. Data from 413 corresponding authors was collected. The focus was mainly on how they discover the journal and what led them to submit a paper to the journal. However, questions concerning their satisfaction with the peer review procedure were also part of the survey. The results have shown that a recommendation of a colleague is not only the main channel through which authors found out about the journal, but is also the major reason they decided to submit their paper to a mega-journal. Furthermore, the quality of the editorial board of the journal, the strong portfolio of papers and the open access concept are also significant factors in encouraging submission to a mega-journal. A majority of the respondents are satisfied with the communication and peer review procedure of the mega-journal, which might encourage new submissions in the future.