Secretory leukocyte protease inhibitor (SLPI) and alpha-1-proteinase inhibitor (alpha-1-PI), both inhibitors of granulocyte elastase, were studied in nasal secretions from healthy persons and from patients with allergic rhinitis and common cold. SLPI and granulocyte elastase were found in all samples, while alpha-1-PI was lacking in several. In all three groups SLPI was found in an active form and in excess of granulocyte elastase, which thus was completely inhibited. The results indicate that SLPI is the main inhibitor in nasal secretions and that alpha-1-PI plays a minor role.