LNCIB has been producing a variety of human full-length-enriched, normalized and subtracted cDNA libraries from various cell lines and tissues in different developmental stages by using the CAP-Trapper method. By sequencing 23000 clones of these libraries we identified a pool of about 5800 good quality unique cDNAs. After BLAST analysis on Human RefSeq/Unigene databases, 1717 of these sequences remained with no or poor annotation. We show that cross-species comparative BLAST resulted as a valid tool for the annotation of orthologous genes.