This study reports the temperature and frequency dependence of dielectric constant (epsilon') and dielectric loss (epsilon'') in glassy Se80-x Te20Sn (x) (x = 0, 2, 4, 6) alloys. The measurements have been made in the frequency range (1-500 KHz) and in the temperature range 305-335 K. The results indicate that the dielectric dispersion exists in the present glassy systems in the above frequency and temperature range. The composition dependence of the dielectric constant, dielectric loss and activation energy thermally activated crystallization is also discussed.