Serum levels of total amylase and P-type, and S-type isoamylase were measured in 57 patients with chronic parotid swelling (41 men and 16 women; mean age 60.4) and the same number of age- and sex-matched control individuals without parotid swelling (41 men and 16 women; mean age 60.3). None of the three enzyme measurements differed significantly between patients with parotid swelling and control subjects. It is concluded that chronic enlargement of parotid glands does not affect serum isoamylase level.