Total aqueous outflow facility was determined by two-level constant pressure perfusion of the anterior chamber for 90 minutes in both eyes of cynomolgus monkeys. Each monkey received Bárány's solution (B, containing no bicarbonate, ascorbate, lactate, urea, sulfate, or amino acids) in one eye and either Gaasterland's (G, containing bicarbonate, ascorbate, lactate, urea, sulfate, and amino acids; 8 monkeys) or modified Gaasterland's (GM, containing ascorbate, lactate, urea, sulfate, and amino acids, but no bicarbonate; 8 monkeys) solution in the other. Starting facility tended to be slightly lower and to exhibit more interanimal variability with G than with B or GM. Perfusion with all three solutions caused a time-dependent facility increase. Facility with G increased approximately 60% during the second 30 minutes, compared to about 15% with B and GM; the difference may have been related to alkalinity and pH instability of G. There were no apparent differences during the final 30 minutes. Solutions containing ascorbate, bicarbonate, lactate, urea, sulfate, and various amino acids conserve facility no better under our perfusion conditions than the much simpler Bárány's solution, indicating that lack of these compounds does not cause the time-dependent facility increase.