Self-diffusion coefficients of the liquid Sn 0.5Te0.5 (in atomic fraction) have been mesu- red. The shear cell technique was employed. Te' SU' grows up to 1100 K and then remains nearly constant. On the contrary D It is.seen that DSnTe SuTe grows linearly up to 1300 K. The results have been qualitatively explained. The possibility of cluster formation in the melt is discussed.