The number of nuclear inelastic interactions of stopping protons in various materials has been calculated using the latest reaction cross-sections. The results are compared with experimental measurements of this effect in silicon, sodium iodide and plastic scintillator and an excellent agreement is found. The calculations are used to determine the loss of counts in proton telescoped due to the presence of absorbers, but the agreement with experimental measurements is satisfactory only for absorbers which are fairly thick (> 50% of the range of the protons). © 1969.