1. Two large-scale community based studies of the haematinic effect of iron added to flour used to bake bread are reported. These were designed to simulate conditions in the community as closely as possible. 2. Neither trial gave conclusive evidence of benefit in terms of an effect on circulating haemoglobin level, but in one trial the results suggested a small haematinic effect. 3. The availability of an iron salt from bread eaten in a normal varied diet is clearly much lower than has been suggested from highly controlled radioactive isotope studies.