The transmission of x-rays through curved cylindrical waveguides is investigated as a function of the guide diameter and the radius of curvature. Measurements were made at

Å using lead glass capillaries with bore diameters ranging from 150 to 250 μ. It was observed, for example, that for a 150 μm diameter capillary 51.5 cm long, the transmission was reduced by a factor e
-1for a radius of curvature equal to 20 m. A model based on meridian ray analysis is presented and compared with the results of the experiment.