1. In a recent paper Karp and Karal(1) have suggested a generalization of the normal impedance boundary condition which might be applicable to surfaces which can support more than one surface wave and have determined the total field produced by a magnetic line dipole placed above an infinite plane characterized by such a condition. The theory is at this stage purely tentative and arguments concerning its plausibility are given in (1). The validity of the generalized impedance condition has also not yet been experimentally verified. From the point of view of experimental verification it would seem useful to have available a theoretical solution valid for an arbitrary electromagnetic field incident on a plane characterized by a generalized impedance condition and such a solution is given in the present note. By means of a technique used by the author in related problems (2,3) an explicit solution is given for an arbitrary incident field and it is shown that the radiation field and the amplitudes of the surface waves may be expressed in terms of the radiation field of the incident wave.