PURPOSE: We report increased interleukin (IL)-6 level in aqueous humor of a case of lung adenocarcinoma with metastasis to iris and anterior chamber. DESIGN: Interventional case report. METHODS: In one case and 11 healthy cataract patients as controls, we checked the levels of IL-6, IL-2, and tumor necrosis factor (TNF)-alpha in aqueous humor and serum by enzyme-linked immunosorbent assay. RESULTS: Levels of these three cytokines in serum were almost the same as with the levels in aqueous humor in the control group. The IL-6 concentrations ranged from 12.6 to 27.0 pg/ml (mean, 23.5 pg/ml) in serum and 15.0 to 43.1 pg/ml (mean, 22.4 pg/ml) in aqueous humor. There was no statistically significant difference between them. Compared with the control, the IL-6 concentration in aqueous humor of this patient, 282.0 pg/ml, increased more than 10,fold. CONCLUSION: This is a report describing elevated IL-6 level in the aqueous humor of a patient with intraocular metastasis from lung adenocarcinoma. (C) 2003 by Elsevier Science Inc. All rights reserved.