Ocular inflammation was induced by 25 microliters of lens proteins (62.5mg/ml) injected into anterior chamber of the rabbit eye. Tetrandrine (Tet) (50mg/kg ip) and Indomethacin (Ind) (20 mg/kg ip) showed marked inhibition on this ocular inflammation. Maximum inhibition rate of Tet and Ind was 65% and 66% and their anti-inflammation action lasted 5 and 4 h, respectively. In the early phase of ocular inflammation (at 2 h) the total content of prostaglandin E(PGES) in the iris was reduced by Tet and Ind. Ind showed a greater effect than Tet on PGES. Tet also inhibited leukocyte chemotaxis significantly at late phase of inflammation. No significant effect was observed on the IOP recovery following reduction by 20% NaCl iv. Topical instillation of 50 microliters of 2% Tet did not display any inhibition of ocular inflammation. These results indicate that Tet is an effective ocular antiinflammatory agent without producing ocular hypertension. The antiinflammatory mechanism of Tet in early phase (at 2 h) was related to inhibition of PGES synthesis. The relationship between ocular anti-inflammation and calcium antagonism of Tet was discussed.