This tutorial was presented during the 1986 training course of the International Pharmaco-EEG Group (IPEG) in Santa Margherita Ligure, Italy. During recent years spectral analysis has been increasingly used in experimental EEG. However, to avoid misinterpretations of results, its limitations must still be carefully considered. The tutorial starts with revisiting the fundamentals of the technique, emphasizes the practical estimation of auto- and cross-spectra, discusses the assumptions underlying the spectral analysis of stochastic processes, and ends with a brief discussion concerning the postprocessing of spectral data