The effects of the adrenergic agonists, norepinephrine, epinephrine, isoproterenol and phenylephrine have been assessed on aqueous humor formation rate (AHFR) and pseudofacility ( C p8 ) in the ganglionectomized rabbit eye. The drug concentrations used were 0·1% as a topical drop. Norepinephrine increased AHFR by 50% and doubled C p8 with no change in intraocular pressure (IOP). Epinephrine caused a 10% decrease in AHFR and an increase in C p8 , also with little change in IOP. Isoproterenol decreased AHFR and increased C p8 , with a fall in IOP. Phenylephrine reduced AHFR and C p8 was unchanged, yet IOP barely changed. Together with in vitro data which indicated that ciliary epithelial permeability does not increase after ganglionectomy the data can be used to estimate other effects of the drugs. It is apparent that ganglionectomy alone must cause an increase in the perfused area of ciliary epithelium and that two major effects of the drugs employed are on true outflow facility and on blood flow through the anterior uvea.