On the basis of Ising theory one would expect the distributions of neutrons scattered from magnetic excitations in substitutionally disordered antiferromagnets to exhibit a multiple‐peaked structure because of the different Ising frequencies associated with the different compositions of the clusters of ions surrounding the magnetic ions. The calculations of Buyers et al. also predict such structure, but other theories predict no structure in the neutron scattering. To resolve the question, we have carried out high‐resolution neutron‐scattering measurements on a single crystal of antiferromagnetic Mn0.32 Zn 0.68F2 using a triple‐axis crystal spectrometer. The measurements were carried out at 5.05 K at a reduced wave vector ζ=0.45 in each of the [00ζ] and [ζ00] directions. Definite structure is observed at both positions. For the [00ζ] direction peaks are observed at 0.23 and 0.47 THz and there is a shoulder at ?0.65 THz. For the [ζ00] direction, there are peaks at 0.30 and 0.50 THz and a shoulder at ?0.70 THz. No existing theory gives an adequate description of the results.