The differential scattering cross section for neutron scattering from liquid heavy water (D2O) has been measured at incident neutron wavelengths of 0·694 and 0·347 Å. The oscillatory pattern observed at high momentum-transfer values characterizes the structure of an individual molecule. The data are found to be in good agreement after application of a correction for molecular recoil and give a value of 0·98 ± 0·01 Å for the oxygen-deuterium bond length.