Haemoglobin (Hb) was measured in 348 full-term one-year-old infants in 7 private paediatric offices. In 36 (10.3%) subjects, the Hb value was less than 110 g/l, and in 7 (2.0%) less than 100 g/l. In 11 of 212 (5.2%) subjects, MCV was less than 70 fl. Twenty-six infants with an Hb below 115 g/l showed an increase of Hb of +10 g/l or more after a therapeutic trial with oral iron. No relationship was found between Hb levels and early introduction of whole cow's milk into the diet. It is concluded that screening for iron deficiency is justified in healthy Swiss infants: Hb and MCV measurements may be the initial step.