Our results demonstrate the following: (1) irbesartan inhibits AOM/DSS-induced colitis, fibrosis and tumourigenesis; (2) this inhibition is associated with a decreased number of CCR2+ monocyte-derived cells, including fibrocytes, infiltrated into the inflamed colon and a reduced expression of Mcp1, Tnfa, Col1a1, Timp1 and Mmp9 in the colon and (3) irbesartan inhibits the formation of colon tumours even when administered after multiple tumours have developed. This evidence concerns the gene MMP9 and infectious otitis media.