The crystal structures of the ilmenite-type oxides, ABiO(3) (A = Na,Ag) were refined using neutron diffraction data. NaBiO3 was prepared by dehydration of NaBiO3. nH(2)O, and AgBiO3 was prepared by ion exchange of NaBiO3. nH(2)O with Ag+ ions. The hexagonal lattice parameters are a = 5.5672(4) and c = 15.989(1) Angstrom for NaBiO(3)and a = 5.641(1) and c = 16.118(2)Angstrom for AgBiO3. The final R factors were R-WP = 11.6 and G(P) = 9.18% for NaBiO3, and R-WP = 7.96 and R-P = 6.12% for AgBiO3.