This study investigated how parents’ preferred level of control in treatment decision-making is related to their personal healthcare involvement and to their decision to use complementary therapies (CTs) for their child. A total of 118 parents of paediatric oncology patients completed an anonymous CT survey. The Krantz Health Opinion Survey (KHOS) was used to determine parents’ preferred involvement in personal health care, and the Control Preferences Scale for Paediatrics (CPS-P) measured preferred role in paediatric treatment decision-making. Most parents preferred active or collaborative decision-making. The KHOS and CPS-P were significantly correlated, indicating that parents’ preferred role in children’s treatment decisions was related to their own personal healthcare involvement. Forty-six per cent of parents used CTs for their child and 33% began using a new CT after diagnosis. The hypothesised relationship between CT use and parents’ own healthcare involvement was partly supported. Preference for control in decision-making was not associated with CT use.