Technological developments in the 21st century have enabled the emergence of tools that enable mass communication. This communication environment has brought about a continuing passion for technology in individuals and, with this passion, a communication pollution and addiction have begun to emerge. In this study, Internet addiction of high school last-grade students studying in Yesilyurt district of Malatya city was analyzed and investigated according to gender and family monthly income. The population of the study consisted of 3442 last-grade students studying in 37 public high schools located in Yesilyurt district of Malatya city in 2016 to 2017 academic year. The sample of the study was composed of 606 last-grade students from 17 high schools randomly selected from the schools in the population. The study model was the survey model. In the study, "Internet Addiction Scale" developed by Günüç (2009) was used to determine the Internet addiction levels of the students. This scale is composed of "withdrawal", "controlling difficulty", "disorder in functionality", and "social isolation" subscales. In the analysis of the data, arithmetic mean (x) frequency (f), standard deviation (sd), k-mean set method, t-test and one-way ANOVA test were used. When these results were taken into consideration, it was observed that majority of the students in the sample were in the non-addicted group (43.3%). A significant difference was determined between gender and Internet addiction mean scores of the students. On the other hand, no significant difference was found between family monthly income and the internet addiction mean scores of the students.