An investigation of the sound field of a corrugated acoustic waveguide has been conducted. The waveguide was constructed by stacking equally spaced circular disks coaxially along a solid rod to form a corrugated cylindrical surface of circular cross section. Measurements of the sound field near the surface of the waveguide show that a dominant mode that has the form of a cylindrical surface wave exists at the corrugated surface. These experimental results are used as the basis both for the development of a theoretical model for the corrugated region of the waveguide and for the theoretical analysis of the farfield radiation pattern of the waveguide. Farfield radiation patterns were measured as a function of the length of the waveguide. These measured patterns are compared to the theoretical radiation patterns. [Work done under a contract with the U. S. Office of Naval Research.]