A total of 334 introgression lines (INLs: BC₃-derived lines) derived from crosses between Indica cultivar IR64 as a recurrent parent and 10 donor parents including new plant type lines (IR6560087-2-2-3, IR65598-112-2, IR65564-2-2-3, IR66750-6-2-1, IR69093-41-2-3-2, IR69125-25-3-1-1, Hoshiaoba, IR66215-44-2-3, IR68522-10-2-2, and IR71195-AC1) have been developed by recurrent backcross breeding, to introduce unique traits into IR64 genetic background and to use for breeding materials. The agronomic traits of the 334 INLs were evaluated in International Rice Research Institute from 2005 to 2007 and the genotypes of the 334 INLs were detected using SSR markers. Particularly, 117 out of the 334 INLs which showed unique agronomic traits were selected as the “core set” for detailed evaluation. Variation in agronomic traits: days to heading (DTH), leaf length and width, culm and panicle length, number of panicles, total spikelet number per panicle (TSN), and 100-grain weight (GW), in the 117 INLs were characterized. As a result of comparison between the several INLs and IR64, significant differences were observed in DTH, TSN and GW in at least one season. The developed INLs with the IR64 genetic background are useful for both breeding and genetic dissection of agronomic traits across various environments.