The diffusivity of Al in ZnSe, ZnSe0.5Te0.5, and ZnTe has been determined in the temperature range of 700°–1000°C. At 1000°C the diffusivities, calculated from the experimental data assuming the Fick's diffusion law to be valid, are (0.66±0.11) × 10−9cm2/sec for ZnSe; (1.2±0.3) × 10−9cm2/sec for ZnSe0.5Te0.5; and (1.3±0.5) × 10−9cm2/sec for ZnTe. The activation energy for diffusion is approximately 2 eV for all three. It is suggested that the diffusion of Al proceeds substitutionally via the Zn sublattice.