||At HKUST, more and more courses are being offered online in different modes: bothas supplements or replacements of the traditional face-to-face learning experience in different degrees. In the meantime, lecturers are under pressure to meet both areas of excellence in research and teaching while, traditionally, the emphasis is placed on the former. Students taking online courses have to meet increasingly demanding academic requirements as well as life-long learning disciplines. As a result of these emerging challenges for both lecturers and students, they will naturally evaluate critically whether technology brings with it opportunities or dilemmas in their course of learning and teaching. As a practitioner in the field of instructional technology at CELT (Center for Enhanced Learning and Teaching), their questions also became mine. Based on the collaboration experiences with HKUST teaching staff and students, this paper highlights some potential opportunities and dilemmas for online learning and teaching in two major areas: - Learning and teaching – self-directed learning, and - Content development – re-purposing atoms to bytes. In cases where dilemmas seemed to be avoidable, this paper also recommended suggestions to minimize them, with the aim of helping lecturers and administrators be more aware and responsive to their challenges.