This study aims to investigate the reasons for learners to drop-out of Open Education System of Anadolu University, Turkey, between 2012-2015. This study uses an exploratory sequential mixed method. The general structure is divided into two phases. In the first phase, the data is collected by semi-structured face-to-face interviews. The results of those interviews are used to design the second phase of the study. According to knowledge gained from the interviews, the reasons of students to drop-out of the Open Education System is organized into categories such as personal, system-related, and environmental. The second phase of the study consists of collecting data via a questionnaire that is created by the knowledge gained in the first phase of the study and from the similar studies in literature. 14,972 learners who had dropped out from the Open Education System, Anadolu University answered the online questionnaire. Some of the results for learners to drop-out might be: unsatisfactory results in exams, lack of knowledge about the open education system, time management issues, unsuitability of the registered program, interference of daily life routines on studies, and some personal problems. Determining the reasons of drop-out of the system and act making the necessary arrangements and updates, may be useful for having a more quality learning experience. Thus, the rates of open and distance learners to drop-out of the system might be reduced.