Between 80 and 90 percent of the asphalt pavement construction projects are the rehabilitation of asphalt pavements that have reached the end of their service lives. These rehabilitationprojects produce about 100 million tons of Recycled Asphalt Pavement (RAP) per year from millings, presenting a major solid waste concern. RAP has an ever-growing value to practitioners in pavement construction. However, limited research exists to quantify the performances of the pavement layers especially for high RAP contents. This paper investigatesthe performance of the pavement base layer having high RAP content using resilient modulus (MR) asthe primary indicatorfor base layer characterization. Testing results of RAP blends was collected from the Minnesota Department of Transportation. Conclusions indicate that RAP has a potential to be used in high percentages in pavement base layer applications. Testing indicates that MR increases with RAP content, with asphaltcontent and with aggregate dry density. Moisture content has less significant effect on the resilient modulusas compared to aggregate sources.