Background: Adolescence is a period that is part of human life in which there is full of dynamics. Adolescence can be characterized by the many curiosity in a person in many ways, not least the field of sex. Premarital sexual behavior in adolescents is influenced by many factors such as age, sex, peer influences, exposure to pornographic media, parent communication, the level of sexual knowledge, religious devotion and self-control. Objective: This study aimed to analyze the factors associated with premarital sexual behavior in students of Nursing at Universitas of Muhammadiyah Yogyakarta. Methods: This study was descriptive correlation with cross sectional approach. Research was conducted in June 2016 in PSIK UMY. The respondents consisted of 225 respondents by stratified random sampling technique. Data analysis were using Chi-square test followed by multivariate logistic regression analysis. Results: Exposure to pornographic media in high category as much as 113 respondents (50.2%), category peer influences higher by 127 respondents (56.4%), Categories of religious observance as high as many as 142 respondents (63.1%), category level sexual knowledge were 116 respondents (51.6%), category parent communication higher by 116 respondents (51.6%), high self-control category as many as 173 respondents (76.9%), and low categories of sexual behavior as much as 142 respondents ( 63.1%). There is a significant association between exposure to pornographic media (p = 0.000), peers (p = 0.000), religious observance (p = 0.007), parent communications (p = 0.007), and self-control (p = 0.000) toward premarital sexual behavior. Factors most associated with premarital sexual behavior is a factor of peers (RO = 2.440), exposure to pornographic media (RO- = 2,039), communication with parents (RO = 0.551), and self-control behavior (RO = 0.408). Conclusions: Factors peer influence is the most dominant factor related to sexual behavior before marriage