Structural, magnetic, and electrical properties are reported for the Na analogue of the doped manganites, La(1-x)A(x)MnO(3) (0.2 < x 0.5, A = Ca, Sr, Ba, Pb), prepared by precipitation from molten NaOH. Elemental analysis and diffraction data are consistent with the composition LaMn0.8Na0.2O3, indicating that Na substitutes almost exclusively onto the Mn sites of the perovskite structure. The magnetic and transport properties of this material have been investigated and it was found that, despite the substitution of a magnetically and electrically inert cation on the Mn site, LaMn0.8Na0.2O3 displays many of the same properties as the manganites doped with divalent cations on the La site. The main property differences are attributed to the strong structural and magnetic disorder that Na induces in LaMno.8Nao.203.