Total outflow facility was measured by two-level constant pressure anterior chamber perfusion in surgically untouched vervet monkeys receiving intracameral infusions of mock aqueous humor without or with isoproterenol. Bolus dl-isoproterenol sulfate doses of 1 to 10 micrograms, corresponding respectively to initial intracameral base concentrations of 2 X 10(-5) M and 2 X 10(-4) M, increased facility 30-50%; higher and lower bolus doses were ineffective, as were 0.1 and 1 g doses of 1-isoproterenol hydrochloride (4 X 10(-6) M and 4 X 10(-5) M base). Relatively maintained intracameral dl-isoproterenol concentrations of 2 X 10(-7) M and 2 X 10(-6) M or l-isoproterenol concentrations of 4 X 10(-7) M to 4 X 10(-5) M did not significantly increase facility, although there was great variability with the latter agent. Possible reasons for species, investigator, technique, and dosage-associated differences in results are discussed.