This paper discusses forced vibrations in an unsymmetric piecewiselinear system excited by general periodic force functions. The system has no damping. The superharmonic resonances up to the second order are analysed by means of a perfect Fourier series method. As the simplest example, the exciting forces are assumed to be of even function with the second higher harmonics only. The theoretical resonance curves are computed by a digital computer and are compared with the results obtained by an analog computer. They show a fairly good agreement.