Background: Non-suicidal self-harm behavior (SHB), which is a pervasive and dangerous problem, is frequent among adolescents and it is important to evaluate the associated psychological and social factors to better understand its nature and to plan treatment programs. Aims: Aim of the present study is to determine the prevalence of SHB and the associated variables such as substance use, psychological, behavioral and social factors among 10th-grade students in Istanbul/Turkey. Methods: Cross-sectional online self-report survey conducted in 45 schools from the 15 districts in Istanbul/Turkey. A representative sample of 4957 10th-grade students was studied between October 2012 and December 2012. Results: SHB within the previous year were reported by 14.4% of the students (n = 713). Lifetime suicidal thoughts or behavior, tobacco, alcohol and/or drug use, symptoms of depression, anxiety and impulsive, delinquent and aggressive behaviors were also associated with SHB in Turkish 10th-grade students. Conclusions: The findings of the present study may be relevant in prevention and management of SHB as well as important problems among students, such as substance use, impulsive, delinquent, aggressive and suicidal behavior.