Objective To test the expression of cyclooxygenase 2 (COX 2) gene in colorectal adenomas, cancers in contrast to that of normal mucosa.[WT5”HZ] Methods [WT5”BZ] With reference to the expression of ? actin gene, the expression of COX 2 mRNA was examined in colorectal adenomas from 10 patients, cancerous tissues and adjacent noncancerous mucosa from 30 patients by reverse transcription polymerase chain reaction (RT PCR). Quantitation of relative band densities was performed using densitometry scanning techniques.[WT5”HZ] Result [WT5”BZ] Strong expression of COX 2 mRNA was detected in ninety percent of cancers with range of 0 02～0 85 (median 0 5). The difference of expression of COX 2 mRNA between cancers and normal mucosa or adenomas was significant (rank sum test, P