The aim of this study was to identify barriers and facilitators to nurses' application of motivational interviewing (MI) to counselling overweight and obese children aged 5 and 7 years, accompanied by their parents. Ten welfare centre and school health service nurses trained and practiced MI for 6 months, then participated in focus group interviews concerning their experiences with applying MI to counselling overweight and obese children. Important barriers were nurses' lack of recognition that overweight and obesity among children constitute a health problem, problem ambivalence among nurses who felt that children's weight might be a problem although there was no immediate motivation to do anything and parents who the nurses believed were unmotivated to deal with their children's weight problem. Facilitators included nurses' recognition of the advantages of MI, parents who were cooperative and aware of the health problem and working with obese children rather than those who were overweight.