Tillering is one of the most important agronomic traits related to grain production in rice (Oryza sativa L.). A japonica-type variety, Aikawa 1, is known to have low-tiller number. The detailed location of a lowtillering gene, Ltn, which has been localized on chromosome 8 in Aikawa 1, was conWrmed by molecular mapping. Using BC5F2 individuals derived from a cross between IR64 and Aikawa 1, the low-tillering gene was mapped to an interval deWned by SSR markers ssr5816-3 and A4765. This was designated as Ltn because there was no reported gene for tillering in the region of chromosome 8. Through high-resolution linkage analysis, the candidate region of Ltn was located between DNA markers ssr6049-23 and ind6049-1 corresponding to 38.6 kbp on the Nipponbare genome sequence. These DNA markers, which were tightly linked to Ltn, are useful for marker-assisted selection in breeding studies.