The propagation of a longitudinal wave in an anisotropic cylindrical bar immersed in water is considered. Energy is leaked into the surrounding fluid in the form of traveling waves, and this leakage determines the amplitude of the signal in the rod. This aspect is important in nondestructive evaluation of composite rods. The governing equation of the longitudinal waves traveling in the rod is obtained and is solved numerically to obtain the dispersion curves and the attenuation, which is due to the energy leaked into the fluid. Results are presented for rods of five different materials.