Cross-section transmission-electron-microscope foils of Type 316 stainless steel have been used t o determine the depth to which voids are formed during proton irradiation at energies between 0.75 and 1.05 MeV. These void depths, which can be determined with an accuracy of t5 percent, have been found to exceed by a rather large amount (∼1 0-4 cm) the results from range-energy data tables prepared specifically for stainless steel. Experimental and micro structural features which could lead to this apparent discrepancy are discussed. It is concluded that the depth to which voids are formed gives a good measure of the proton range at a particular energy. Values of calculated proton energy vs penetration which best agree with the experimental depth data are presented.