Background To examine whether ethnicity moderates the association between caregiver characteristics and perceptions of childhood weight and whether these perceptions are associated with their child's obesity status. Methods Caregivers recruited from paediatricians' offices (n = 453) completed a survey about childhood health; nurses weighed and measured the children. Caregivers reported their own weight and height, demographic information about their family and made ratings of healthy weight for children in general and for their own child in particular. Results African American caregivers were more likely to view heavier girls as healthier, but this association held only for lower income families or caregivers with higher body mass index. Hispanic caregivers were more likely to misperceive their own child's weight if either the caregiver or the child had a higher body mass index. Parents who perceived heavier weight as healthier or misperceived their own child's weight were more likely to have a child with obesity. This latter association held regardless of ethnicity. Conclusion The association between ethnicity and perceptions of healthy childhood weight are complex. The relation between caregivers' perceptions of healthy weight and their own child's obesity status, however, was similar regardless of ethnicity.