This research aims to find out the students’ perception on online discussion in English teaching and learning at English Language Education Department of a private university in Yogyakarta. The objectives of research were to ascertain the advantages, disadvantages and also the difficulties faced by the students in doing online group discussion based on the students’ perception. It was conducted at ELED of a private university involving three students batch 2015. The participants were selected with some criteria, which is students who experienced in online discussion and also participated in the discussion. The activeness really helped the researcher to collect the rich data. The students’ activeness defined the experiences in the activity. This research used case study as a research design under qualitative method to present the finding. The researcher conducted the open-ended interview. The research had three findings. The first finding was about the advantages of doing online group discussion. Those were about the students’ experiences, satisfying, and the strengths of online discussion itself. The second finding was about the disadvantages of doing online group discussion. The disadvantages based on the students’ perception would be around the students’ anxiety, frustration and disappointment. The last finding was about the difficulties in online group discussion which were about the internet connection, writing skill and the teacher’s instruction understanding.