Objective The results of studies concerning levels of internalizing and externalizing behaviors in adolescent children with a parent suffering from cancer as compared with control groups or normative data are contradictory so far. Longitudinal designs using control groups are rare. No study explicitly exploring a broad range of risk behaviors in adolescent children with a parent suffering from cancer exists to date. Methods Therefore, 74 adolescents who have a parent with cancer (index group) were compared with 75 adolescents with healthy parents (control group) concerning several juvenile risk behaviors and externalizing behaviors. Participants were examined three times over the course of 12 months. Results No significant main effects for group or interactional effects of group with time could be found for any of the measured variables. Conclusions Results suggest that the somatic illness of the parent is not a developmental risk that is expressed in increased levels of juvenile risk behavior. Adolescents with a parent suffering from cancer adjusted generally quite well to the parental illness, although some individuals did show signs of severe strain. Copyright © 2013 John Wiley & Sons, Ltd.