Using the activitation method (n,2n) excitation-functions were measured for54Fe,70Ge,74Se,85Rb,8688Sr,89Y,92Mo, and204Hg in the neutron-energy region 13–18 MeV. The results are checked for consistency by means of a systematic of (n, 2n) cross-sections as a function of the nuclear neutron excess (N-Z)/A. Furthermore the data are compared with results from the statistical nuclear reactions theory which were calculated using optical model absorption cross-sections and the Fermi-gas-model formula for the nuclear level density. In the case of204Hg the influence of preequilibrium nucleon emission was taken into account.