Objectives: The aim of this study was to identify characteristics of children and adolescents who were victims of sexual assault in Korea. Methods: The subjects were 60 children and adolescents who visited the one-stop center as victims of sexual assault. The medical records of victims of sexual trauma were retrospectively reviewed. We studied the demographic data of the victims, their relationship to their perpetrator, the characteristics of the assault (frequency, duration, place, type), and the process from sexual assault to treatment. We also paid special attention to how the characteristics of the victims or perpetrators affected the characteristics of the assault or follow-up treatment. Results: There were several differences between sexual assaults committed by strangers and those committed by acquaintances. Sexual assaults committed by acquaintances lasted for a longer period of time than those committed by strangers. In addition, it took more time for victims of sexual assaults committed by acquaintances to seek treatment than those who were victims of sexual assaults committed by strangers. The majority (55.0%) of victims were between 10 and 15 years of age. Forty percent of the perpetrators were teenagers, and two of them were under the age of 10. Voluntary discontinuation of treatment was more frequent in adolescents than in children. Conclusion: All teenage victims of sexual assault need some sort of urgent intervention. In addition, approachable methods are needed in order to prevent sexual abuse by strangers or acquaintances.