The diet of pre-school children is determined by the parents and carers. The aim of the present study was to describe dietary clusters of pre-school children and their mothers in Finland, and analyse the similarity of dietary clusters within child–mother pairs. The present study comprised the mothers (n 4862) whose child was recruited in the Type 1 Diabetes Prediction and Prevention Nutrition Study and the children belonging to selected, cross-sectional age groups of 1 year (n 719), 3 years (n 708) and 6 years (n 841). The dietary data were collected from children by 3-d food records and from mothers by a FFQ validated for pregnant women. The food consumption data were analysed for patterns by hierarchical cluster analysis. Three main dietary clusters were identified in children: ‘healthy’ and ‘traditional’ in all three age groups, and ‘ready-to-eat baby foods’ in 1-year-olds and ‘fast foods, sweet’ in the older children. Six main clusters were identified among the mothers who completed a FFQ for their diet during pregnancy. Some familial dependence between dietary clusters of mother–child pairs was observed in 6-year-old children but not in younger children. Younger age and lower educational level of the mother were associated with the cluster ‘fast food, sweet’ only at the age of 3 years. The diets of pre-school children vary by age and only a slight similarity within dietary clusters of mother–child pairs was observed.