Opportunistic growth measurements have been recommended in the UK to complement universal measurement of a child’s growth at school entry. This study analysed the effectiveness of opportunistic growth measurements in a random sample of 200 children attending hospital for clinical reasons other than growth concerns. Height and weight were measured in only 12.5% and 51.5% of the children, respectively, and head circumference in 11.1% of the children below the age of 2 years. The levels of height measurement were equally poor in all clinical areas, while significantly fewer children had weight measurements in outpatients and non-Paediatric areas. The results suggest that the opportunity to check a child’s growth is seldom used in hospital settings. There is a need for an education programme for health professionals to emphasise the value of growth as an index of health in children, and for the current strategy for growth monitoring in the UK to be re-evaluated.