The neutron-induced fission cross section of U-235 is not only one of the most-frequently used references but is also of direct importance in reactor applications. As a consequence, knowledge of this cross section is required with approx. 1% uncertainty as reflected in corresponding entries in request lists, which have persisted since the last 10 to 15 years. Measurements to that level of accuracy require the investigation of the contributing components, one of which is the fission mass. The latter is most often determined by others than the experimenter who measures the differential cross sections or integral reaction-rate ratios in a reactor test facility. The isotopic composition and the sample mass are usually obtained from associated chemistry departments or standard laboratories, however, the experimenter has still the responsibility to assure that the values he uses are adequately described by the quoted uncertainties. This can be achieved by comparing samples from different origins. It was in this spirit that an intercomparison of fission samples obtained from different US laboratories, which were involved in cross section measurements, was carried out in 1979. The notable outcome of this effort was that a bias of approx. 0.7% was found between the standard laboratory and other contributing laboratories (which was, however, within the stated uncertainty). The National Bureau of Standards (NBS) has since then worked on a redefinition of the mass assignments of its reference samples, has revised its mass scale by 0.8%, and has reduced its uncertainty by a factor of two (to about +-0.5%). However, this new mass scale includes values relative to others. In the present work these have been removed in order to compare mass scales as independent from one another as possible. Independence already appears hard to come by. Results are presented. (WHK
