Flurbiprofen is a water-soluble, non-steroid anti-inflammatory agent and is capable of marked inhibition of prostaglandin synthesis. In a previous study by the authors, it was determined that the optimum concentration of flurbiprofen for intraocular irrigation solution in monkey retinas is 4 to 40 micrograms/ml. The present study was conducted to determine the optimum concentration of flurbiprofen for the irrigation solution, as well as to evaluate its toxic effects on the anterior segment tissues. In a pilot experiment, flurbiprofen was injected directly into the anterior chamber of pigmented Japanese rabbits to investigate its overall toxicity and to quantify the concentration at which it could become toxic to the cornea. This experiment showed that aqueous concentrations of flurbiprofen greater than 1,000 micrograms/ml were toxic. In a subsequent study, the twelve eyes of six Japanese monkeys (Macaca fuscata) underwent vitrectomy using balanced salt solution (BSS) containing concentrations of flurbiprofen from 4 to 800 micrograms/ml and BSS alone. This experiment showed that BSS containing 4 to 100 micrograms/ml of flurbiprofen prevented post-operative occurrence of edema in non-pigmented epithelial cells in the ciliary body. Furthermore, it was observed that infiltration of inflammatory cells into the trabecular meshwork and swollen mitochondria in the corneal endothelial cells were likewise prevented. This is thought to be due to the pharmacological action of flurbiprofen; which has an inhibitory effect on leucocyte migration and prostaglandin synthesis as well as stabilization of the cell membrane. However, these effects were not observed in the eyes vitrectomized with flurbiprofen concentrations between 400 and 800 micrograms/ml.(ABSTRACT TRUNCATED AT 250 WORDS)