Objectives: This study aimed to determine the relative risks of addiction to the Internet, online gaming and online social networking of college students in six Asian countries/regions (Singapore, Hong Kong [HK]/Macau, China, South Korea, Taiwan and Japan) compared with students in the United States (US). It also explored the relative risks of depression and anxiety symptoms among students with Internet-related addictions from these countries/regions. Study design: This is a cross-sectional survey. Methods: A convenience sample of 8067 college students aged between 18 and 30 years was recruited from seven countries/regions. Students completed a survey about their use of the Internet, online gaming and online social networking as well as the presence of depression and anxiety symptoms. Results: For all students, the overall prevalence rates were 8.9% for Internet use addiction, 19.0% for online gaming addiction and 33.1% for online social networking addiction. Compared with the US students, Asian students showed higher risks of online social networking addiction but displayed lower risks of online gaming addiction (with the exception of students from HK/Macau). Chinese and Japanese students also showed higher risks of Internet addiction compared with the US students. In general, addicted Asian students were at higher risks of depression than the addicted US students, especially among Asian students who were addicted to online gaming. Addicted Asian students were at lower risks of anxiety than the addicted US students, especially among Asian students who were addicted to online social networking, and addicted students from HK/Macau and Japan were more likely to have higher relative risks of depression. Conclusions: There are country/regional differences in the risks of Internet-related addictions and psychiatric symptoms. It is suggested that country/region-specific health education programmes regarding Internet-related addictions are warranted to maximise the efficiency of prevention and intervention. These programmes should attempt to tackle not only problematic Internet-related behaviours but also mood disturbances among college students.