In view of the importance of so-called “sequential reactions”in fusion reactor structural materials, the production of radioactivity due to sequential reactions associated with protons emitted via (n,xp) reactions with 14.9-MeV neutrons has been measured. The effective production yields with respect to 14.9-MeV incident neutrons produced by sequential reactions were obtained for the radio active products of 48 V, 56Co, and 64Zn in titanium, iron, and copper, respectively. The values were 14.7 ± 1.9, 4.6 ±0.3, and 11.4 ± 1.9 μb, respectively. The effective production cross section was estimated on the basis of all relevant data on (n,xp) and (p,n) cross sections, proton emission spectra, and the proton stopping power in these materials. This analysis gave values 22% larger, 29% smaller, and a factor of 5.6 smaller than the measured values for these reactions, respectively. The range of these discrepancies is not unreasonable considering the large uncertainties in the data base used in the estimation.