This study was designed to explore the risk factors of Internet addiction in 1360 freshmen of the National Cheng Kung University in Taiwan in 2003. The test battery included a self-administrated structured questionnaire, the Chinese Internet Addiction Scale-Revision (CIAS-R), the 12-item Chinese Health Questionnaire (CHQ-12), the Measurement of Support Functions (MSF), and the neuroticism subscale of the Maudsley Personality Inventory (MPI). Of the total study population, there were 680 college freshmen (17.9%) in the Internet addiction group, as defined by high CIAS-R scores. Using logistic regression analyses, we found positive relationships between Internet addiction and male gender, neuroticism scores and the CHQ score. In addition, the freshmen who skipped breakfast and those who had poorer social support also had a higher probability of Internet addiction. Internet addiction is prevalent among university freshmen in Taiwan. Risk factors included male gender, habit of skipping breakfast, mental health morbidity, deficient social support; and neurotic personality characteristics.