Introduction Iron deficiency is a critical issue in calves. This study was conducted to assess the iron supply of dairy calves compared with that of fattening calves. Materials and Methods Blood samples were taken from 118 heifer calves on twenty-one dairy farms in the Innviertel, a part of Upper Austria. Calves older than 16 weeks of age and those that had received any treatment with iron containing drugs in the previous 7 days were excluded from the study. Haematocrit, haemoglobin and plasma iron concentration were measured. A questionnaire was completed relating to housing, feeding, health and medical treatment of the calves on each farm. Results Iron deficiency anaemia was detected in a substantial proportion of the heifer calves. In 43.2 % and 17.8 of the cases, haematocrit and haemoglobin were either moderately or severely decreased. A deficiency of iron in the plasma was detected in 44.9 % of the calves. The lowest concentrations were found between the fifth and the eighth week of life, after which the measured parameters steadily increased until 16 weeks of age. The feeding of milk replacer instead of milk had a positive effect on haematocrit, haemoglobin and plasma iron concentration. There was a significant increase in the haemoglobin concentration when the calves, in accordance with legal requirements, were supplied with hay or grain, at the beginning of the second week of life at the latest. There was an evident positive effect of the prophylactic application of iron supplements. Calves that received iron-containing substances showed significantly higher blood haematocrit, haemoglobin and iron concentration than calves without any prophylactic measures. Conclusions Iron deficiency anaemia has an important role in heifer calves and needs to be considered in veterinary practice. In addition to treating the individual animals suffering from iron deficiency, it appears necessary to improve prophylactic and management measures in cattle farming, especially in feeding of young calves.