The concentrations of immunoglobulins (Ig) A, G and M were measured in saliva using an electro-immunodiffusion technique at pH 5 with carbamylation of the antisera. Thirty-one controls and 20 patients with generalised scleroderma (10 with and 10 without Sjögren's syndrome) were studied. The three classes of immunoglobulins were in normal saliva. A concentration of IgG greater than 55 mg/l in whole saliva was associated with Sjörgren's syndrome. This is the consequence of the reduction of the rate of saliva production, as well as an increased local synthesis of IgG. The measurement of IgG in unconcentrated saliva could be useful in the detection of Sjögren's syndrome.