Abstract: Introduction Production of functional mRNAs in eukaryotic organisms is critically dependent upon the accuracy of pre-mRNA splicing. The presence of well-defined cis-elements, namely the 5’ and 3’ splice sites and the branch point, is necessary but not sufficient to define intron-exon boundaries (1). Sequences within exon bodies have a prominent role in promoting exon definition; the best understood exonic elements are represented by exonic splicing enhancers (ESE) which represent binding sites for SR proteins (2). Sequences that act as exonic splicing silencer (ESS) have also been described but are less well characterized than ESEs. It has been reported that pseudoexons (i.e. intronic sequences displaying good 3’ and 5’ splice sites) outnumber real exons by an order of magnitude (3). Recent observations (4, 5) suggest that a subpopulation of pseudoexons might exist in the human genome requiring only subtle changes to become splicing competent. Here we have applied a biocomputational approach to address the question of why pseudoexons are ignored and to identify putative splicing repressor elements.