PC/ABS blends have been widely used for specific applications such as in automotive interior & exterior parts and office automation equipment parts. In this study, the effects of a reactive polymer as a modifier on the properties of PC/ABS blends were investigated. The reaction between PC and maleic anhydride group cannot be expected usually because the end hydroxyl group of PC is capped with end-capping agents such as t-butyl phenol to improve the properties of PC. However, we have found that a reactive polymer which has maleic anhydride group reacted with the end hydroxyl group of PC which was hydrolyzed with metal salts. From the results, the impact strength of PC/ABS was improved with the reactive polymer.