Transient global ischemia causes neurogenesis in the dentate gyrus of adult rodents. Ischemic insults to rodents also induce cyclooxygenase-2 (COX-2), an isoform of cyclooxygenases (COXs) and a rate-limiting enzyme for prostanoid synthesis. In the present experiments, adult Mongolian gerbils were chronically treated with acetylsalicylic acid (ASA), a non-selective COX inhibitor, and the proliferation of cells in the dentate gyrus was examined under ischemia. It was proved that BrdU-labeled cells in the dentate gyrus were significantly reduced in number following ASA treatment after 10 min global ischemia. The result strongly suggests that COX, probably COX-2, and prostanoids play an important role in the proliferation of neural cells after ischemia in gerbils.