In this paper, interpolation of linear predictive coding (LPC) parameters in terms of the following representations is investigated: linear prediction coefficient representation, reflection coefficient representation, log-area-ratio representation, arc-sine reflection coefficient representation, cepstral coefficient representation, line spectral frequency representation, autocorrelation coefficient representation and impulse response representation. Though each of these representations provides equivalent information about the LPC spectral envelope, their interpolation performance is found to be different. It is shown that the line spectral frequency representation results in the best interpolation performance.