The ground state Q value of the reaction Ni58(7Li, He8)57Cu has been measured and found to be -29.613(17) MeV. This corresponds to a Cu57 atomic mass excess of -47.303(15) MeV. At a beam energy of 76.5 MeV and a scattering angle of 7, the observed cross section was 17 nb/sr. The implications of these results are discussed. 1986 The American Physical Society.