Total 4He production cross-section measurements have been made for 6Li and 7Li for 15-MeV neutrons. Isotopically enriched samples of lithium metal were bombarded with an intense flux of T(d,n) neutrons from a rotating target neutron source. Following the irradiation, the accumulated 4He was determined by isotope-dilution mass spectrometry. The lithium samples and the incident neutron spectrum were accurately characterized, both by experimental methods and by calculational simulations. The measured 4He production cross sections are 0.512 ± 0.026 b for 6Li and 0.336 ± 0.016 b for 7Li, at an average neutron energy of 14.95 MeV.