The 5' cap structure of RNA polymerase II transcripts and the poly(A) tail found at the 3' end of most mRNAs have been demonstrated to play multiple roles in gene expression and its regulation. In the first part of this review we will concentrate on the role played by the cap in pre-mRNA splicing and how it may contribute to efficient and specific substrate recognition. In the second half, we will discuss the roles that polyadenylation has been demonstrated to play in RNA metabolism and will concentrate in particular on an elegant mechanism where regulation of polyadenylation is used to control gene expression.