Dislocation structures in olivines from three pallasite meteorites (Admire, Brenhan and Dora) were observed. Results are as follows: (1) Dislocation densities are very low (?1¿106 cm-2) compared to those of terrestrial olivine. (2) Dislocations are mostly curved. (3) Subboundaries are well developed. (4) The slip system determined from the dislocation dipole and sub-boundaries is (010)[100>. (5) There are helical dislocations. (6) Dislocation densities and spacing of sub-boundaries have either a powerlaw relation or one characteristic of annealing. These observations all imply that the olivines from pallasites were annealed, that they have experienced high temperature deformation at low strain rate within parent bodies during the course of cooling, and that differential stresses which cause deformation can not have exceeded several times ten bars since then. Dislocations in olivine grains from pallasites are not of impact origin but are due to deformation within parent bodies.