The removal of intervening sequences from pre-mRNA is an important step in gene regulation. Pre-mRNA processing takes place within the spliceosome, a dynamic structure composed of small nuclear RNA (snRNA) and proteins. The function of the spliceosome is currently being studied in many eukaryotic systems including mammal and yeast. Here we review pre-mRNA splicing in fission yeast and man and propose that spliceosomal structure and function has been evolutionarily conserved between the two organisms.