There is a debate in the health outcomes literature regarding who the most appropriate respondent is when assessing children's health-related quality of life (HRQoL). In some cases, parent-proxy may be the only practical option where children are unable to self-complete an HRQoL questionnaire. However, children's self-reported values may be preferable because HRQoL is subjective and represents the respondent own perception of health. We collected the youth version of the EQ-5D-3L as part of a feasibility study comparing psychoanalytic child psychotherapy with usual care for children aged 5-11 years with treatment resistant conduct disorders. The questionnaires were completed at baseline and 4-month follow-up by the child via face-to-face researcher administration, and by one parent as a proxy respondent. We present percentages of completion at each time-point and investigate the level of agreement between child and proxy-respondent on the child's health. About two thirds of children (65.5%) were able to complete the EQ-5D-Y at baseline and 34.4% at follow-up. Children and primary carers were mostly concordant regarding overall child's health. Parents reported more problems in 'doing usual activities' and 'feeling worried, sad or unhappy' and fewer problems with 'pain' and 'looking after oneself' than children did. The reports regarding 'mobility' were very similar between children and proxy-respondents. The assessment of quality of life by children using selfreport questionnaires is possible with the help of a face-to-face researcher, providing evidence that children should be asked to self-complete HRQoL questionnaires in trial studies.