A method for complex interpolation of FT NMR spectra is presented. The technique assumes the periodic extension of a complex spectral segment and makes use of a discrete Fourier transformation. Spectral resolution is increased to the predicted 1/THz, where T is the acquisition time, for previously nonzero supplemented FID's. In addition, spectral definition of peak positions, intensities and linewidths is enhanced. This procedure significantly reduces additional computer data storage requirements over that of the more conventional interpolation technique of zero filling and is easily implemented on existing NMR computer systems.