The examination of gene expression in colorectal cancer may develop the bases of early diagnosis and of individual therapeutic strategies. With the few cDNA microarray examinations in colorectal cancer the expression of hundreds and thousands of genes were studied, although both the sample collection and the final results showed differences. Beside the exposition of the practical advantages of the chip technology our aims are the standardization of the currently available data in the international scientific literature and the description of the results in a comprehensible way. To summarize one can say that gene expression examinations in colorectal cancer show the accentuated role in carcinogenesis of not only the tumor suppressor, apoptosis- or cell-cycle regulation related genes, but of some mitochondrial, metabolic and cell-cell or cell-extracellular matrix conjunction gene families.