The crystal structures of the two layered ferroelectric oxides A(0.875)Pb(0.125)Bi(2)Nb(2)O(9) A = Sr and Ba have been refined using both powder neutron and multiple wavelength synchrotron powder diffraction data. At room temperature both lead doped oxides have an orthorhombic structure with space group A2(1)am. Bulk samples of the two oxides exhibit small, but significant amounts of disorder involving both the A type atoms and the Bi atoms, with the Pb atoms being exclusively located within the Bi2O2 layers.