Teleost fishes are the largest and most diverse group of vertebrates. The diversity of teleosts has been attributed to a whole-genome duplication (WGD) event in the ray-finned fish lineage. Recent comparative genomic studies have revealed that teleost genomes have experienced frequent gene-linkage disruptions compared to other vertebrates, and that protein-coding sequences in teleosts are evolving faster than in mammals, irrespective of their duplication status. A significant number of conserved noncoding elements (CNEs) shared between cartilaginous fishes and tetrapods have diverged beyond recognition in teleost fishes. The divergence of CNEs seems to have been initiated in basal ray-finned fishes before the WGD. The fast evolving singleton and duplicated genes as well as the divergent CNEs might have contributed to the diversity of teleost fishes.