We evaluated if the theory of planned behavior explains students` activity in a web-based learning environment. Two of the considerations of the theory, attitude toward the behavior (behavioral beliefs and outcome evaluations) and perceived behavioral control (computer self-efficacy), were evaluated. The scope was also widened to students' approaches to learning and anxiety in computer using situations as well as their interpretations of the environment and the learning situation. Forty-two undergraduate medical and sociology students completed the questionnaire assessing attitudes, self-efficacy, anxiety and approaches to learning before and after the web-based courses. The attitude toward the behavior, efficacy beliefs, approaches to learning and anxiety in computer using situations did not predict the activity in the learning environment, but students interpreted the environment and the learning situation more negatively after the courses. Students' anxiety and approaches to learning also affect some of their expectations and experiences after the courses.