The predominant inhibitors of granulocyte elastase in plasma (alpha 1-proteinase inhibitor and alpha 2-macroglobulin) together with antileukoproteinase were quantified in parotid secretion and mixed saliva. Antileukoproteinase was the only inhibitor found in parotid saliva and was present in a concentration about 30 times the serum level, suggesting a local production. In mixed saliva, antileukoproteinase accounted for more than 70% of the molar concentration of the granulocyte elastase inhibitors studied. alpha 1-Proteinase inhibitor was measurable in about 1/3 of the specimens of mixed saliva. In parotid secretion, antileukoproteinase was present only as a free, active inhibitor. In mixed saliva about 15% of antileukoproteinase was in complex with granulocyte elastase, while the remaining amount of 85% was inhibitorily active. This suggests that antileukoproteinase has a biological function in a local defence mechanism directed towards the effects of granulocyte elastase in the oral cavity and salivary glands.