A number of investigators have studied the effect of metabolic inhibitors on the facility of aqueous outflow from the enucleated eye perfused eye at "room temperature". Some inhibitors such as iodoacetate and iodoacetamide increased the facility, others such as p-chloromercuri-benzoate decreased it. Most however, including sodium fluoride, were reported to have had no effect. We have found that 10 mM sodium fluoride had a very small effect on facility of aqueous outflow at room temperature (22 degrees C), but reduced the facility as much as 50% (average 30%) at 35 degrees C. The magnitude of the sodium fluoride effect did not appear to be dependent on calcium levels in the medium, but the presence of Ca2+ significantly prolonged its duration. Iodoacetamide and iodoacetate both increased facility at 35 degrees C in a manner similar to previous findings at room temperature except that at 8-10 mM, iodoacetate caused a 55% decrease; under these conditions, there was considerable release of tissue debris into the anterior chamber which probably blocked the TM. A number of other agents, such as 2,4-dinitrophenol, KCN, and 2-deoxyglucose were studied, but none produced any marked effect on facility. These results emphasize that temperature may profoundly modify the effect of metabolically active agents. The mechanism of the fluoride effect has not been determined but it is consistent with the action of F on the G protein associated with phospholipase C.