With the advancement in Information and communication Technology Online education systems and Massive open online course (MOOC) are expanding rapidly. Learners form different backgrounds are joining these courses with different motives. Inspite of massive enrollments the platforms offering these courses are facing many challenges. One of the major challenge that needs attention is dropout. There may be different reason for different learner to dropout from a course. These reasons may be independent or dependent on each other. In this paper existing studies are reviewed to find out the reasons of dropout from online courses. Around 40 factors were identified that can facilitate a learners decision to dropout from course. These factors are grouped in to five main categories Social, family, personal, institutional, Technical