Explorable areas concerning actual impacts of computer usage on various types of related activities after school on student learning, and relationship between time spent on those activities and student personality styles (in terms of social and intellectual selves and learning attitudes) have still been under-researched in local and international perspectives. This study aims to fill up these research gaps by studying 528 Secondary 1-3 (Grade 7-9) students, aged from 12 to 16, in a secondary school in Hong Kong in terms of a questionnaire to record their activities on using computers after school and to identify their personality styles in Hong Kong. By taking mid-term school examination results for granted, the study not only reveals correlation between examination marks and time using computers, but also depicts variation of their participating activities on using computers. Copyright © 2006 The authors. All rights reserved.