The antioxidant activity of saliva has been investigated in 28 apparently healthy individuals and seven dental patients with periodontal disease. The results show that the major aqueous antioxidant component of whole saliva is uric acid, with lesser contributions from ascorbic acid and albumin. All are present at lower concentrations than those found in the plasma water. The total antioxidant activity (TAA) of saliva correlates (r2= 0.972) with the concentration of uric acid, which contributes more than 70% of the TAA. Stimulation of salivary flow is associated with increased production of antioxidants. The antioxidant potential of saliva does not appear to be compromised in patients with periodontal disease but this may relate to the antioxidant flow from the gingival crevicular fluid.