Photoluminescence spectra of diffusion layers of zinc-doped indium phosphide were investigated. A study was made of diffusion layers obtained in different regimes. A diffusion process was conducted for 30 and 60 min at temperatures of 450–500°C. The photoluminescence spectra consisted of bands with E1=1.145 eV, E2=1.37 eV, E3=1.345 eV, E4=1.15 eV. Photoluminescence was measured at 77 K upon excitation by laser radiation at 0.44 μm. An analysis is made of the regularities of the change in the spectral dependences for samples with different prehistories by using layer-by-layer etching as well as of the change in the integral Zn activation energy for different temperatures of postdiffusion annealing.