Galvanomagnetic effects are investigated in n-type Pbl -,Sn,Te with comparatively low carrier concentration (1.4 x 10' ' t o 3.5 x 10'8cm-3) grown from the melt. From the analysis of the longitudinal and transverse magnetoresistances and Hall coefficient a t low temperatures together with the Shubnikov-de Haas data, it is found that the scattering is very much isotropic in spite of the large anisotropy of the effective mass. Further analysis of the scattering relaxation time, z, indicates that the alloy scattering is dominant a t low tmperatures. The inatrix elements of the alloy scattering potential a t the band edges are deduced; U,(Pb-Sn) = 8.