Color Doppler ultrasonography has numerous potential applications in the diagnosis and monitoring of many ocular disease processes. One of its advantages over other investigative and diagnostic tests is its safety and repeatability. To be able to fully assess this technique it is important to have good control data and to know the reproducibility of the technique for each of the retrobulbar vessels. Color Doppler ultrasonography was performed on 80 volunteers, and normal ranges of blood velocity were calculated for the ophthalmic artery and for the central retinal artery and vein. Reduction in the peak systolic and end diastolic velocities in the ophthalmic artery and an increase in resistive index in the central retinal artery and vein were noted with advancing age. With regard to reproducibility of the retrobulbar vessels, 15 healthy persons were chosen at random and intra- and interobserver studies performed. The most reliable and reproducible vessels were the ophthalmic artery and central retinal artery and vein. Greater variation was noted in the posterior ciliary vessels, whereas the superior ophthalmic and vortex veins were unreliable in both detection and velocity measurement. The results provide normal ranges for future studies and demonstrate that reproducible results can be obtained for the orbital vasculature using color Doppler imaging.