Objective Gene-environment interactions that moderate aggressive behavior have been identified in association with the MAOA (monoamine oxidase A) gene. The present study examined the moderating effect of MAOA-VNTR (variable number of tandem repeats) on aggression behavior relating to child abuse among Chinese adolescents. Materials and methods A sample of 507 healthy Chinese male adolescents completed the Child Trauma Questionnaire-Short Form (CTQ-SF) and Youth Self-report of the Child Behavior Checklist. The participants' buccal cells were sampled and subjected to DNA analysis. The effects of childhood abuse (CTQ-SF scores), MAOA-VNTR [ high-activity allele (H) versus low-activity allele (L)], and their interaction in aggressive behaviors were analyzed by linear regression. Results Child maltreatment was found to be a significant independent factor in the manifestation of aggressive behavior, whereas MAOA activity was not. There was a significant interaction between MAOA-VNTR and childhood maltreatment in the exhibition of aggressive behaviors. In the context of physical or emotional abuse, boys in the MAOA-L group showed a greater tendency toward aggression than those in the MAOA-H group. Conclusion Aggressive behavior arising from childhood maltreatment is moderated by MAOA-VNTR, which may be differentially sensitive to the subtype of childhood maltreatment experienced, among Chinese adolescents. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.