This study assesses the stability of dietary patterns obtained using principal components analysis (PCA) through early to mid-childhood. Dietary data were collected from children in the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC). Frequency of consumption of a range of food items was recorded by mothers using self-completion postal questionnaires when their children were 3, 4, 7 and 9 years of age. Dietary patterns were identified using PCA and component scores were calculated at each time-point. In total 6177 children had data available at all four time-points. Three patterns were consistently seen across time: the 'processed', 'traditional' and 'health conscious' patterns. At 3 years an additional 'snack' pattern was obtained and at 9 years the 'health conscious' pattern was slightly modified (meat products were negatively associated). High correlations were evident for all three scores between each pair of time-points. The widest limits of agreement were seen for all pairings between the 3 and 9 years data, whilst the narrowest were seen between the 4 and 7 years data. A reasonable level of agreement was seen with the categorised component scores from each time-point of data (kappa ranging from 0.28 to 0.47). Virtually identical dietary patterns were obtained at the ages of 4 and 7; however, periods of change were apparent between the ages of 3 and 4 and the ages of 7 and 9. It is important to make regular dietary assessments during childhood in order to assess accurately the effects of diet on future health outcomes.