Atopic keratoconjunctivitis (AKC) is a chronic allergic eye disease. Although the pathogenesis is not fully understood, some impairment in cell-mediated immunity was suggested by histopathological findings in conjunctival specimens obtained from affected individuals. T-cell infiltration and an enhanced T-helper/T-suppressor cell ratio in conjunctival biopsy specimens were observed previously by immunofluorescence procedures. We analyzed the cells in tears of patients with AKC using flow cytometry (FCM) and compared the results to those of normal subjects to identify the role of T lymphocytes in the pathogenesis of the disease. The tear samples of the patients and normal subjects were collected with capillary tubes, and the surface receptors of cells were detected with FCM. Statistical analyses were performed with Student’s t test. The percentages of T cells, activated B cells, and T-helper/T-suppressor cell ratios were found to be higher in the tears of patients with AKC than in controls. We propose that a decreased T-suppressor cell concentration in tears may enhance immunoglobulin-E production of B cells, and the signs and symptoms are provoked by inflammatory mediators liberated from mast cell degranulation.