The serum total immunoglobulin E (IgE) concentrations of two groups of atopic dogs and three groups of non-atopic dogs were compared. There was a wide range of concentrations with a high degree of overlap between the groups. The serum total IgE concentrations of a group of 15 non-atopic racing greyhounds were significantly higher than those of all the other groups. Atopic and non-atopic dogs receiving stringent parasite control treatments could not be differentiated on the basis of their serum total IgE concentrations. In the non-atopic dogs there was no correlation between their serum total IgE concentrations and the number of allergen-specific positive results obtained in an ELISA, or between their serum total IgE concentrations and their age.