In order to investigate lymph drainage from the retrobulbar space colloid solutions (198Au-colloid and 99mTc-sulfur-colloid) were injected into the right retrobulbar space of 31 rabbits. The distribution of radioactivity was measured in vitro after dissection with a sodium iodine crystal well counter and in some animals in vivo with the Gamma camera. More than 90% of the applied activity of either colloid solution was found in some animals up to the eighth day post injection in the retrobulbar space and in the liver. The remaining activity was recovered mainly from the regional lymph nodes, due to its smaller particle size higher values were registered in the experiments with 198Au than in those with 99mTc. The highest concentrations with up to 4,6% of the activity were observed in the deep cervical lymph nodes on both sides. Minor concentrations of activity were found ipsilateral in the superficial cervical and mandibular lymph nodes. Furthermore, small but significant activities were demonstrated in the optic nerves as well as in the contralateral retrobulbar space. The present data clearly substantiate the existence of lymph drainage, although a slow one, from the retrobulbar space. Moreover they indicate a reverse prelymphatic-lymphatic flow toward the optic nerves and the contralateral retrobulbar space. These results are of importance in the discussions of lymphostatic ophthalmopathy. The clinical application of this method is desirable; however, at present it is not yet practicable without further studies.