An immunohistological study was performed on allergic (A) and non-allergic (NA) nasal mucosa to examine the profiles of infiltrating T-lymphocytes and their association with the expression of ICAM-1. Higher numbers of CD4 and CD45RO positive cells were detected in the A group than in the NA group, especially in the superficial portion of the lamina propria (SUP), whereas the number of CD8 positive cells was the same in the two groups. ICAM-1 was noted mainly on the vascular endothelium and on the infiltrating cells in the SUP, and there was no difference in the intensity of its expression between the A and NA groups. However, the infiltration of CD4 and CD45RO positive cells in the SUP and around the glands was significantly greater in patients with intense ICAM-1 expression in the A group. The infiltration of CD8 positive cells did not differ among the patient groups with different intensities of ICAM-1 expression in the A and NA groups.