Objective: To evaluate how a motivational interviewing (MI) training course for child healthcare nurses in Sweden affected their work with children's weight issues and their attitudes to MI. Design: Cross-sectional survey, descriptive design. Setting: Nurses were recruited from 33 different child healthcare centres in Ostergotland, Sweden. Method: Seventy-six nurses who had participated in an MI training course (held in 2008) were approached one year later to answer a questionnaire by telephone. Most questions concerned the respondents' routine use of MI in clinical practice and their attitudes towards MI as a method. Results: The response rate was 82 per cent. Nearly half of the nurses had changed the content and structure of their discussions regarding weight issues. Three-quarters of the nurses stated that they had sufficient time to use MI and that they had support from leadership and colleagues to use MI in their routine practice. The nurses' attitudes to MI were positive, especially their perception that MI was consistent with their values and was better than traditional advice-giving approaches. Most MI techniques were found to be simple to use: 78 per cent found it very or quite simple to listen actively, 63 per cent believed it was very or quite simple to summarize parents' opinions, 63 per cent found it very or quite simple to pay attention to parents' change talk, and 60 per cent said that it was very or quite simple to ask permission before providing information. Conclusion: MI training can have a substantial effect on child healthcare nurses' clinical work on paediatric weight issues. (Contains 3 tables.)