Two groups of 22 budgerigars (Melopsittacus undulatus) were housed for 12 months under identical conditions. One group was fed a commercial seed mixture plus carrots and a mineral supplement, and the other group was fed a commercially formulated diet plus carrots. Samples of blood and faeces were collected initially and after three, six, nine and 12 months. There were no significant differences between the haematological values of the two groups. The group fed the seed mixture had significantly higher concentrations of glucose, albumin, triglycerides and uric acid, and higher activity of aspartate aminotransferase, but the values were within the published reference ranges for normal birds. There were no significant differences between the faecal samples from the two groups, except that the fungus Macrorhabdus ornithogaster was identified in 48·3 per cent of the samples from the group fed the commercially formulated diet but from only 3·4 per cent of the samples from the group fed the seed mixture.