A novel mapping population structure (identity-by-descent (IBD) limited recombinant inbred lines) has previously been proposed by our group for mapping quantitative trait loci, which involves reducing the amount of genome surveyed. This results in permitting smaller population sizes and screening of fewer molecular markers. The primary objectives of this study is to use the IBD limited recombinant inbred lines (RILs) in testcross condition to identify QTLs for corn grain yield. A population of 128 IBD limited RILs were developed from a sister line cross between CG60 and CG108 (both Iodent) and each were crossed to CG102 (Stiff stalk). Field experiments were planted as an RCBD at three locations and two replications. Single factor analysis of variance was used to identify significant trait-marker associations. Molecular marker data indicates that the two sister lines CG60 and CG108 are ~70% identical by descent, while significantly differing in grain yield. The non-IBD regions were present as small linkage blocks. Although only 30% of the genome was segregating between the parents, the IBD limited RILs exhibited a wide range of phenotypic variation for grain yield, from 94.1 to 141.4 bu/ac, with evidence of negative epistatsis and no RIL yielding as much as higher yielding parent CG108. Eight simple sequence markers (SSR) were significantly associated with grain yield QTL; and as expected, smaller effect grain yield QTLs were identified (1.4 to 6.6 bu/ac yield contribution). The concept and development of identity-by-descent limited recombinant inbred line population, and its usefulness will also be discussed.