Purpose: This study was done to identify predictive factors influencing suicide probability in Korean adolescents. Methods: Participants in the study were 575 adolescents from 17 schools with quota sampling by each region in D city. The data were collected from October to November, 2010 using self-report questionnaires about interpersonal relationships and suicide probability (SPS) and analyzed using descriptive statistics, one-way ANOVA with Scheffe of Post Hoc, Pearson`s correlation coefficients, and stepwise multiple regression analysis with SPSS/WIN 16.0 program. Results: Suicide probability showed a significantly negative correlation for interpersonal relations with parents, friends and teachers. Interpersonal relationship with parents (p<.001) explained 32% of suicide probability, compared to relationships with peers or teachers, which together was accounted for 46% of the variance. Conclusion: The findings suggest that interpersonal relationships with parents should be considered when adolescents suffer from suicidal thinking. Various effective strategies to improve relationships with parents are important to reduce suicide in adolescents.