Routine full blood counts and serum ferritin determinations were carried out after admission to hospital in 112 children which included a white caucasian group (n = 65) and two ethnic minority groups of West Indians (n = 24) and Asians (n = 23). In these 3 groups those children between the ages of 1 week and 6 months were found to have similar haemoglobin, mean corpuscular volume, and ferritin levels. In the remaining children (aged from 7 months to 14 years 5 months) serum ferritin levels were lower in the ethnic minority groups than in white caucasians, but the haemoglobin and mean corpuscular volume were not significantly different. Children with lower height centiles had reduced ferritin levels, irrespective of their ethnic origins. A nutritional survey between the ages of 7 months and 14 years 5 months showed that mean daily dietary intakes of energy, protein, and iron in white caucasions were similar to those in West Indian and Asian children. The differences noted were in larger phytate and fibre intakes in the ethnic minority groups. Asian diets appeared to differ in containing meat less often as a source of iron, while pulses and chapattis provided more phytate and fibre. It is suggested that dietary intakes of phytate and fibre are important in causing lower ferritin levels by reducing iron absorption.