This study is concerned with online learners' "low" experiences. On the basis of Csikszentmihalyi's theory of flow, flow was conceptualised as a complex, multimentional, reflective construct composing of "enjoyment", "telepresence", "focused attention", "engagement" and "time distortion" on the part of learners. A flow model was put forward with regard to virtual class environment in a traditional university context, comprised with flow antecedents, flow and flow consequences. Based on the model, a virtual-course flow measure was developed and administered to 525 undergraduate students engaged in virtual classes in order to examine the empirical relationships between measured flow antecedents, flow experiences and flow consequence-course satisfaction in this case. The analysis of the data showed that: (1) students' perceptions of their level of "skill" and "challenge" specific to each course are critical to determining the level of flow, (2) flow is a significant predictor of course satisfaction and (3) other than flow, individual differences such as "gender" and "having a clear goal" can make a significant difference in the level of flow in a virtual course. These findings are discussed along with the implications for bringing up a computer-mediated environment more conducive to flow and learning.