Internet addiction is a novel and relatively uninvestigated form of dependence that is fairly common in adolescent population. Previous research has indicated that it may be associated with other mental health problems, such as dysthymic mood and narcissistic behavior. In our study, we tested the existence and strength of relationship between Internet addiction, self-esteem and narcissism in a student population. On a sample of 244 students, we also investigated social networking activities, such as number of self-portrait photographs ("selfies"), and their potential connection with self-esteem and narcissism. Each participant completed a questionnaire consisting of Young Internet Addiction Test, Rosenberg Self-Esteem scale, and Narcissistic Personality Inventory. There was a statistically significant negative correlation between internet addiction score and self-esteem. Internet addiction increased as self-esteem decreased and vice versa. On the other hand, there was a positive correlation between internet addiction and narcissism. NPI score and number of self-portrait photographs (selfies) on Facebook were also in a positive relationship. Conversely, NPI score increased as the self-esteem decreased. The results of the study are in accordance with our previous findings on Internet use and mental health, confirming that Internet addiction is a potentially a serious public health problem.