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Composition changes that occur during neutron bombardment have been calculated for the first wall of a hypothetical fusion reactor. The first wall materials studied are pure niobium, zirconium, molybdenum, and vanadium, and some of their binary alloys. Two integrated neutron flux intensities, 3.8 x 10$sup 14$ n/(cm$sup 2$ sec) and 3.8 x 10$sup 15$ n/(cm$sup 2$ sec) up to a fluence of 3.6 x 10$sup 23$ n/cm$sup 2$, have been used in the calculations of the first three materials. In addition, the composition as a function of fluence (maximum fluence = 4.0 x 10$sup 23$ n/cm$sup 2$) has been calculated for a vanadium wall. Graphs for each material have been plotted to show the variation of composition as a function of time and/or fluence. Rates of production of hydrogen and helium have been calculated for all four materials; comparisons for niobium and vanadium walls with literature values show agreement that it is not poor. Furthermore, mixture diagrams have been constructed for two binary alloy systems, niobium- zirconium and niobium-vanadium, to relate composition at constant irradiation time to the initial composition.