BACKGROUND: Endotoxin-induced uveitis (EIU) is a model for acute anterior uveitis associated with a variety of pro-inflammatory cytokines and nitric oxide production. Interleukin 10 (IL-10) down-regulates these inflammatory mediators. We report a study of the effect of systemic administration of IL-10 on the inflammatory parameters of EIU. METHODS: Uveitis was induced in C3H/HeN mice by subcutaneous injection of 200 micrograms lipopolysaccharide (LPS) per mouse. Intraocular inflammation was assessed by leukocyte count and measurement of the protein concentration in the aqueous humor (AH). Mouse recombinant IL-10 at 1000 U or its vehicle alone were administered by three intravenous injections given 4.0 h and 0.5 h before and 8.0 h after LPS injection. RESULTS: The inflammatory cell infiltration in the eyes was significantly reduced in four of five experiments from 40% to 64% in the groups treated with IL-10 compared to the control groups (P < 0.05). In contrast, the level of protein exudation in the anterior chamber (AC) was not significantly affected by IL-10 treatment. CONCLUSION: IL-10 reduces the cellular infiltration in the ocular inflammation produced by endotoxin. This result suggests potential usefulness for IL-10 in the treatment of severe anterior uveitis with a strong cellular component.