Gene frequencies and haplotypes for two factor IX markers, F9-192 and F9-Hha1, were determined in a Chinese population. The frequencies for F9-192 are 0.86 for A and 0.14 for G. For F9-Hha1, the gene frequencies are 0.69 for - and 0.31 for +. Haplotype analysis revealed that the two polymorphic sites are in linkage equilibrium and, thus, are useful markers for genetic counseling of Asian families in which hemophilia B exists.