Triplet energy migration in poly[(9-phenanthrylmethyl methacrylate)-co-(methyl methacrylate)] films has been investigated by time-resolved phosphorescence spectroscopy in the temperature range 15-100 K. Phosphorescence spectra from tripler trap sites were slightly shifted toward the low-energy side with the elapse of time. The spectral shift was simulated by the Monte Carlo method. The simulation reproduced experimental data, which allowed estimation of the dispersity of the site energies. Due to homogeneous broadening, the distribution function became broader with the increase of temperature.