The relationship between child- and parent-reported quality of life (QOL) and the effects of parental mental health, illness stressors, and child vulnerability was explored using two measures of QOL: the Pediatric Cancer Quality Life-32 (Varni et al., 1998a) and the Disquol (Eiser, Cotter, Oades, Seamark, & Smith, 1999). Thirty-two children with acute lymphoblastic leukaemia (mean age = 8·92 years) and 36 parents completed measures of QOL when attending routine clinic. In addition, parents also completed the General Health Questionnaire (GHQ-28), perception of the child's vulnerability, and illness-related stressors. Significant correlations were found between the overall scores on the two child-completed QOL measures, with a range of poor, moderate to good correlations found between the individual subscales. Poor to moderate concordance was found between child and parent reports. Children who self-reported poorer QOL had mothers who were more depressed. Parents who reported poorer QOL for their child reported more illness stressors and perceived their child as being more vulnerable. Assumptions that concordance between child and parent ratings of QOL is a necessary requirement for new measures of QOL are challenged.