Weedy rice (Oryza sativa f. spontanea) is an important resource for breeding and evolutionary studies. The present study was carried out to identify the genotype of weedy rice strains responsible for variation of pericarp color by sequencing exon 6 of the Rc gene. Haplotype analysis revealed that rice strains with light red- and red-pericarp lacked the 14 bp deletion in the Rc gene, while rice strains with white-, brown and light green-pericarp contained the 14 bp deletion. A single nucleotide polymorphism (C→A SNP) in exon 6 of the Rc gene was not found in all the weedy rice strains examined. This indicates that white pericarp allele in weedy rice gene pools of today might have originated by gene flow from locally grown modern rice varieties with white pericap into established gene pools of wild rice.