Given the prevalence of Internet use among youth, there is concern that a subset of Internet-using youth may exhibit problematic or addictive patterns of Internet use. The present study examines the association between problematic Internet use (PIU), demographic variables, and health-related measures among Chinese adolescents. Survey data from 1552 adolescents (male = 653, mean age = 15.43 years) from Jilin Province, China, were collected. According to the Young Diagnostic Questionnaire for Internet Addiction (YDQ), 77.8% (n=1,207), 16.8% (n=260), and 5.5% (n=85) showed adaptive, maladaptive, and problematic Internet use, respectively. Multinomial logistic regression analysis revealed that gender and family income per month differed between youth showing problematic and adaptive patterns of Internet use. Well-being, self-esteem, and self-control were related to severity of problematic Internet use, with greater severity typically associated with poorer measures in each domain. The findings that severity of problematic Internet use is associated with specific socio-demographic features and temperamental and well-being measures suggest that specific groups of youth may be particularly vulnerable to developing problematic Internet use. Early prevention/intervention programs targeting at-risk groups may help improve public health.