A new method of sequence analysis, using a weight array method (WAM), which generalizes the traditional Staden weight matrix method (WMM), is proposed. With the help of a statistical mechanical model, the discriminant function is ident with the energy function describing macromolecular interactions. The method is applied to the study of 5′-splice signals in Schizosaccharomyces pombe pre-mRNA sequences. The results show that there may exist weak pairwise correlations within the signals and that our method can help to better discriminate these signals. Experiments are proposed to test the predictions of the theory.