Although the pathogenesis of Crohn's disease remains yet clarified, impaired immunologic stimuli in intestinal mucosa may play an important role in the disease. T cell receptor repertoire, which recognizes antigens in conjunction with class II MHC molecules, reflects characteristics of antigenic stimuli related to the disease. In lamina propria lymphocytes in patients with Crohn's disease, skewing in T cell receptor V beta repertoire was confirmed in T cell clones generated from early aphtous lesion. Most of them showed oligoclonal expansion in some subsets of V beta. These results suggest that lamina propria lymphocytes were selectively stimulated by the local antigens closely related to the pathogenesis of the disease.