Protein-DNA complexes called nucleosomes are fundamental building blocks of chromatin. They package a long eukaryotic genome into tiny chromosomes. More interestingly, recent years have brought an insight into the role of nucleosomes in the regulation of gene expression. An important regulatory feature of the nucleosome is its positioning. We have used a sequence-based algorithm to study nucleosome positioning around regulatory sites. The results indicate a role of nucleosome positioning in the protection of splice junctions and in the switch mechanism over TATA boxes.