The tacticity of poly(maleic acid) has been resolved by 150-MHz C-13 NMR spectroscopy in 0.1 N HCl solution at 60 degrees C by using the chemical shifts from the backbone carbon atoms and the carboxyl carbon atoms. The racemic propagation is found to be preferred by a factor 2 over mesomeric propagation. The resonances of the carboxyl carbon atoms can be assigned to configurations of heptad sequences along the polymer chain.