Narcissists show up daily on a television, in magazines, on internet sites. It seems that narcissism is on the rise, especially among adolescents and young adults. Research have shown that the current generation of adolescents and young adults are more narcissistic than the previous generations. Not only that adolescents are more narcissistic, they are also the main consumers of social network sites, which raises the question of whether there is a connection between narcissism and social network sites usage. Therefore, the aim of this study was to examine the relationship between narcissism and some aspects of using the most popular social network among adolescents - Instagram. We also wanted to examine whether there are gender differences in self-presentation and time spent on Instagram. The survey was conducted on 225 students of the Commerce School in Čakovec, who completed the Narcissistic personality questionnaire (NPI), the Scale of the dark triad, the Intensity of Instagram usage, and the Instagram conduct questionnaire adapted for the purpose of this research. The results of the study found a positive correlation between narcissism and emotional attachment, time spent on Instagram, self-presentation and social contact, while between narcissism and the number of followers and the number of people that are followed, on Instagram there was no correlation. Those respondents who achieved higher scores on the narcissism scales were more emotionally connected with Instagram, spent more time on Instagram, and participated in multiple self-promotional behaviors and more behaviors that served to maintain social contacts. When it comes to gender differences in the use of Instagram, it was found that young women and young men differ in self-presentation and the time they spend on Instagram; a larger number of young women spend more hours on Instagram, while the opposite effect is noticed for young men. Also, young women are more likely to engage in self-promotional behavior on Instagram when compared to young men.