Dynamic radionuclide sialography (DRS) provides data about the aptitude of salivary glands to accumulate the tracer and to secrete the saliva. Visual interpretation of the t/a curves may be onerous when salivary glands uptake function is impaired. The purpose of the study has been to quantify the ascorbic acid (AA) response by means of salivary excretion index (SEI). DRS was performed in 10 healthy subjects and in 118 patients with various diseases of the parotid glands. Data acquisition (80 frames/15 s) started simultaneously with i.v. administration of 99mTcO4. Fifteen minutes later AA was given per os. Regions of interest were set over parotid glands. SEI was derived using the formula: SEI = (2b-a-c)/b, where a, b and c were cpm 3 minutes prior, in the moment when, and 3 minutes after AA was given. In 9 of 10 controls SEI was greater than 55 (mean = 63.2). Results in patients with Sjögren's and Mikulicz's syndrome and sialoadenitis, were significantly lower than in healthy subjects. Lowest results were found in patients with sialolithiasis. It may be concluded that SEI improves objective assessment of the AA response particularly in patients with minute or asymmetric disorders of salivary glands function.