Resected inflamed gingival tissue obtained from 16 periodontal patients and a pooled sample of noninflamed gingiva from five edentulous patients were assayed for immunoglobulins IgG, IgA, and IgM using low-level immunodiffusion plates. Findings based on the gingival assays include:(1) IgA and IgG are present in both inflamed and normal gingiva and although their levels are substanitally higher in the inflamed gingiva, their ratio, one to another, remains the same; (2) IgM can not be consistently demonstrated in inflamed gingiva with the assay technique employed: (3) local immune response exists in the inflamed gingiva of humans with chronic periodontal disease; and (4) there is an unknown homeostatic mechanism which regulates the globulin levels in states of health and inflammation. Further study is needed to correlate clinical impressions with histological and quantitative measure of immunoglobulin levels in the inflamed gingiva and to investigate the role of delayed hypersensitivity in the disease process. Work must also be directed toward the detection of specific antigens responsible for elicting the immune response in the gingival tissue of the periodontal patient.