A total of 182 parents and 23 adolescent patients participated in Precision Medicine for Children with Cancer (PRISM), an Australian precision medicine clinical trial for high-risk childhood cancer . We analyzed the mixed-methods data comprising measures exploring families’ perceptions and understanding of PRISM’s participant information sheet and consent form (PISCF), and factors associated with understanding . Many suggested improvements including the use of clearer language and a more visually engaging format . Parents from culturally and/or linguistically diverse backgrounds had lower actual understanding scores than those from a Western/European background whose first language was English .