Abstract An estimation method is described for generating the spectral response curves of a NaI scintillation detector to monoenergetic gamma-rays. The principle of the method is (1) response curves are decomposed to become a linear combination of some intrinsic-component patterns, (2) the interpolation of response curves is then reduced to a simple interpolation of weighting coefficients, and (3) the estimate of any response curve within an energy range is generated by utilizing only the principal-component patterns and the interpolated weighting coefficients. Heath's response spectral library is used to develop the practical generation procedure. The accuracy of the estimated responce curves is discussed in detail, and an effective implementation of the procedure on a computer is devised. A computer simulation is performed to demonstrate the availability of these curves for the analysis of complex pulse-height spectra.