The goals of this study were to evaluate the effect of orally administered amino acid-chelated iron (Fe) compared to injected Fe-dextran on haematology and weight gain in two different breeds raised under commercial condnions. Altogether 92 Duroc (D) pigs and 84 Norwegian Landrace (L) pigs from two different herds were included in the study. The day after birth the litters were divided in two groups (split litters). Group (Gr.) 1 was given 4ml of a 50% solution of super Fe-MAX@ (52 mg glutamic acid-chelated Fe in a water solution) orally, while Gr. 2 was subcutaneously (s.c.) injected with Idofer@ (18Omg Fe as ferridextran). Until weaning at 5 weeks, all the piglets had free access to a 3% solution of Super Fe-MAX@ (0.78 mg Fe/ml), access to pelleted food being given from 1 week of age. The piglets were weighed and bled before treatment the day after birth (day 1) and on days 4,7, 14,21 and 35. All piglets were weighed on days 28 and 49, whle 72 of the L pigs were also weighed on days 77,98 and 11 9. At weaning D pigs in Gr. 1 and Gr. 2 had a mean body weight of 8.64 kg and 8.30 kg, respectively, the corresponding figures for the L pigs being 10.82 kg and 10.34 kg. As regards the 72 L pigs followed to day 119, the mean weight in Gr. 1 and Gr. 2 was 80.6 kg and 80.2 kg, respectively. A significantly lower weight gain in the piglets with a birth weight below 1.2 kg in Gr. 2 compared with Gr. 1 indicated that excess administration of Fe to small piglets may have a detrimental effect on weight p n . From day 7 (D pigs) and on days 14 and 21 (L pigs), Gr. 2 had a significantly higher haemoglobin concentration (Hb) than Gr. 1. Nevertheless, Hb levels were also adequate in Gr. 1 in both breeds. There was a negative correlation between changes in Hb during the first weeks and the initial value. Though haematological values seemed to show inter-breed differences, with higher average erythrocyte counts (RBC) and Hb and lower mean cell volume (MCV) in the D pigs, the ability to avoid Fe deficiency nevertheless appeared to be the same in both breeds.