Background Rising rates of childhood obesity have become a pressing issue in public health, threatening both the mental and physical well-being of children. Attempts to address this problem are multifaceted, and in England include the National Child Measurement Programme (NCMP) which assesses weight status in English primary school children in reception class (aged 4-5) and in year 6 (aged 10-11), with results being sent out to parents. However the effectiveness and impact of this routine parental feedback has yet to be fully understood. This paper reports one component of a mixed methods study undertaken in North East England, examining the impact of the feedback letters on parents’ understanding and feelings about their child’s weight status and whether or not this seemed likely to lead to behaviour change. Methods One-to-one semi-structured interviews (n=16) were conducted with a sample of parents/guardians after they had received their child’s weight results letter. Eight parents/guardians were sub-sampled from the group whose child had been indicated to be overweight or obese and eight were from the group whose child had been indicated to be of ideal weight status. Interviews were conducted until data saturation was reached for both groups. Results The reactions of parents/guardians whose children were identified as being overweight followed a sequence of behaviours ranging from shock, disgust with the programme, through denial and self-blame to acceptance, worry and intention to seek help. On the other hand, the reaction of parents/guardians whose children were identified as being ideal weight ranged from relief, pleasure and happiness through affirmation and self-congratulation to ‘othering’. Conclusions Whilst overweight and obesity is often portrayed as a medical condition, parents/guardians see it as deeply rooted in their social lives and not in health terms. Parents believe that the causes of overeating and lack of exercise relate closely to the obesogenic environment, particularly the complex social and cultural milieu and time pressures within which this sample of people live. Associating this problem in feedback letters with dangerous diseases like cancer, and advising parents to visit GPs to resolve child weight issues was perceived as inappropriate by the parents, and caused controversy and anger. Given the likelihood that the NCMP will continue as a monitoring device, it is evident that the management of the process needs to be reviewed, with particular attention being paid to the feedback process. Local health authorities will need to manage parental expectations and ensure linkage with appropriately commissioned remedial weight management interventions.