The propagation of plane electromagnetic waves in a bianisotropic material is considered. The dispersion relation for a general bianisotropic medium is derived directly in the (x,y,z) system. A detailed analytic knowledge of the coefficients of the dispersion equation can be of great interest in fields of application, such as material synthesis. The general result obtained here is especially useful in studying reflection and transmission for planar multilayered structures of bianisotropic materials. >