In the present study we evaluated the expression of the HTRA1-3 genes, encoding human HtrA serine proteases HtrA1, HtrA2, and HtrA3 isoforms (HtrA3L and HtrA3S), at both mRNA and protein levels, in colorectal tumor tissue and unchanged colorectal mucosa of the CRC patients. This evidence concerns the gene HTRA1 and colorectal carcinoma.