A cross-sectional study was carried out to determine the prevalence of iron deficiency among healthy Saudi children from birth to 15 months of age. The groups studied were: newborns, 3-4 months, 5-6 months, 7-8 months, 9-10 months and 12-15 months of age. The age groups were dictated by the vaccination schedule. Serum ferritin was measured and transferrin saturation calculated in each subject. The lower limits of normal were taken as a transferrin saturation of less than 10% and a serum ferritin of less than 12 micrograms/l. A total of 333 serum samples was adequate for analysis. None of the newborns or the 3-4-month-old infants had evidence of iron deficiency. At 5-6 months only 3.3% of subjects had iron deficiency. In the subsequent older age groups the prevalence of iron deficiency increased significantly with age from 9.3% to 12.7% and reached 14.5% in the oldest age group. Screening for iron deficiency in children attending well-baby clinics and hospitals at ages of 12-15 months is recommended.