ABSTRACT Aim The aims of this study were to determine the levels of cigarette smoking, psychoactive substances, game, and internet addiction among high school students and to examine whether addictions show a significant difference according to some socio-demographic variables and the relationships between addiction types. Method A total of 530 high school students studying in Turkey, agreed to participate in the study. Data were collected through face-to-face interviews using the Sociodemographic Questionnaire (which contains DSM-V categories of addictive substances), Fagerström Test for Nicotine Dependence (FTND), Game Addiction Scale (GAS), and Internet Addiction Test (IAT). Results Approximately 1.9% of the respondents were smokers and 0.8% were inhalant users. Respondents scored 7.43 ± 2.88 on FTND, 13.92 ± 5.57 on the GAS, and 43.44 ± 18.80 on the IAT. Male respondents received a higher average score on the GAS than female respondents, and female respondents received a higher average score on the IAT than male respondents. As body mass index increased, a statistically significant, positive and moderate correlation was found between GAS scores and IAT scores. Conclusion Addictions are becoming more and more widespread and measures, information, and research should be increased and young people should be educated about addictions.