Mucosa-associated lymphoid tissue (MALT) lymphomas usually arise from acquired MALT induced by chronic inflammation or autoimmune processes. In MALT of the gastrointestinal tract lymphocyte homing mechanisms operate primarily through interactions between integrin, expressed on mucosal lymphocytes, and MAdCAM-1, expressed on endothelium of high endothelial venules (HEV). In the present study, the expression of MAdCAM-1 and peripheral lymph node vascular addressin (PNAd) was examined immunohistochemically in normal, inflamed and MALT lymphoma tissues of various organs. It was shown that MAdCAM-1 was expressed on HEV in the gastrointestinal tract and thyroid that are inflamed or affected with MALT lymphomas, but not in the ocular adnexa, lung, and salivary gland. In contrast, PNAd was consistently expressed in all of the inflammatory or lymphomatous lesions examined, but not in the normal tissues. Expression of MAdCAM-1 on HEY may play an important role in lymphocyte migration at sites of chronic inflammation or MALT lymphoma of the gastrointestinal tract and thyroid. In other organs, PNAd may have the greater role.