The aim of the study was to elucidate whether the HtrA1, HtrA2, HtrA3L, and HtrA3S proteins are implicated in colorectal oncogenesis by evaluation of expression of the HTRA1, HTRA2, HTRA3 genes at the mRNA and protein levels, and the estimation of possible correlations between the expression levels of the tested genes and clinicopathological characteristics of the patients, microsatellite status of a tumor and survival data. This evidence concerns the gene HTRA1 and neoplasm.