This study was performed to assess the level of ozone risk for wheat and potato in the central region of the Korean Peninsula by using ozone indices, the ozone-concentration based index (AOT40). The AOT40 indices were calculated for wheat and potato, respectively, at 25 sites in the central region of the Korean Peninsula during a period of three months from April 1 to June 30, 2006. The results for both indices, AOT40, showed that agricultural crops could be seriously damaged by ozone in the central region of the Korean Peninsula. In the result of AOT40, ozone may affect about 60% of the sites for wheat and 20% of the 25 sites for potato.