The purpose of this study is to examine the relationships between high school students' internet addiction, social media usage disorder, and smartphone addiction. The descriptive relational scanning model, one of the quantitative research methods, was used to determine this relationship. The research was carried out with 215 students who continue their education in the field of information technologies of 4 state vocational high schools in the province of Siirt in the 2018-2019 academic year. In this research, internet addiction, social media usage disorder, and smartphone addiction scales were used as data collection tools. The research data were analysed with the SPSS statistical calculation program. As a result of the research, it was observed that high school students' internet addiction, social media usage disorder, and smartphone addiction are moderate and similar in terms of gender and class levels. In the study, a positive relationship was found between high school students' internet addiction, social media usage disorder, and smartphone addiction. It was also found that all three problems were the predictors of each other. The findings were discussed with the literature along with some recommendations.