Rice ( Oryza sativa) cultivar development currently faces the task of overcoming yield plateaus, which is difficult due to the narrow genetic base of breeding programs. Oryza glumaepatula is a diploid wild relative of cultivated rice, native to Central and South America, and is therefore a potential source of alleles of agronomic importance to rice breeding programs. We studied 11 agronomic traits in BC(2)F(2) families of the interspecific cross Oryza sativa x O. glumaepatula. Transgressive lines which are almost isogenic to the elite recurrent O. sativa parent were identified for most of these traits. Quantitative trait locus (QTL) analysis was performed by single-point and interval mapping using a molecular map based on 157 microsatellite and STS markers. Marker regions accounting for 14.5 to 72.9% of a phenotypic variation trait were identified in 9 of the 12 rice chromosomes. Positive QTL effects from O. glumaepatula were observed in chromosomal regions associated with tillering and panicle-number traits.