Fourteen calves were used to investigate the changes from birth to 83 days of age in the concentrations of serum albumin, alkaline phosphatase, beta-hydroxybutyrate, plasma cortisol, serum creatine kinase, creatinine, iron, plasma fibrinogen, serum gamma-glutamyl transferase, plasma glucose, haptoglobin, serum non-esterified fatty acids, total protein, transferrin, triglycerides, urea and gamma globulin; the haematological variables measured were: basophils, eosinophils, haematocrit, haemoglobin, lymphocytes, mean cell haemoglobin, mean cell haemoglobin concentration, mean cell volume, monocytes, band neutrophils, neutrophils, platelets, red blood cells and white blood cells. The changes are presented as a series of graphs and the values are discussed in relation to the published reference ranges for adult cattle. Two populations of calves were identified which gave rise to a bimodal distribution for some of the variables. Differences in haematocrit, haemoglobin and red blood cell counts were apparent at birth, with raised values for these measurements being associated with an increased white blood cell and neutrophil count between three and 27 days of age.