The use of optical contact as a low‐loss acoustic bond at gigacycle‐per‐second frequencies has been demonstrated. The reflection of 3‐ and 9 Gc sec longitudinal waves from an optical contact bond between two X cut quartz rods has been measured to be of the order of 1% of the incident acoustic power at 1.5°K. Thin X‐cut quartz disks optically contacted to Z‐cut quartz and ruby rods have been used at 1.5°K and found to be about as efficient aa an X‐cut rod.