Genes are continually being created by the processes of genome duplication (ohnolog) and gene duplication (paralog)Whole-genome duplications have been found to be widespread in plant species and play an important role in plant evolution. Clearly un-overlapping duplicated blocks of whole-genome duplications can be detected in the genome of sequenced rice (Oryza sativa).Syntenic ohnolog pairs (ohnologues) of the whole-genome duplications in rice were identified based on their syntenic duplicate lines.The paralogs of ohnologues were further scanned using multi-round reciprocal BLAST best-hit searching (E＜e-14). The results indicated that an average of 0.55 sister paralogs could be found for every ohnologue in rice. These results suggest that small-scale duplications, as well as whole-genome duplications, play a significant role in the two duplicated rice genomes.