After partially injecting the anterior chamber with a 0.2% fluorescein-Ringer solution we examined using a blue filter slitlamp normal eyes, eyes with open-angle glaucoma, and eyes following iridectomy, iridencleisis, Elliot's trephination, and trabeculectomy. In normal eyes at physiological intraocular pressure, 1--9 aqueous veins were found with a mean of 4.6. The distribution of these veins was usually irregular, being more numerous and of largest caliber in the lower nasal quadrant. With only a few exceptions the aqueous veins originated 1--2 1/2 mm peripheral from the limbus and joined the episcleral veins after a short course. The venae recipientes were characterized by a straight and deep course. In eyes with an open-angle glaucoma the average number of aqueous veins was found to be increased compared to the number found in healthy eyes. However, the caliber of these veins was smaller and distribution mor uniform. Eyes having undergone iridectomy do not differ from normal eyes in the mechanism of aqueous humor outflow. After iridencleisis and after trephination the transport of aqueous humor from the anterior chamber is achieved through a filtration bleb: (1) transconjunctival, (2) by bulk-flow through lymphatic vessels, (3) diffusely through lymphatic vessels or veins. In most cases the different transport mechanisms were combined and pure types were seldom found. There was a very definite relationship found between the size of the filtration bleb and the development of draining lymphatic vessels. After trabeculectomy the following drainage mechanisms of the aqueous humor were observed: 1. Subconjunctival outflow of aqueous humor. The further drainage in this case was achieved as in the old types of fistula building operations i.e., primarily through the lymphatic vessels. 2. Direct transport of aqueous humor into the surgical area through newly incorporated veins and lymphatic vessels. 3. Drainage of aqueous humor through still functioning aqueous veins.