Grain boundaries in indium antimonide with misfit angles of 6° have been prepared which, according to the dislocation model for grain boundaries, consist of rows of &agr; or &bgr; dislocations. Current flow across these boundaries inn‐ andp‐type material has been studied. Alpha boundaries were found to present a barrier to current flow inn‐ andp‐type material, &bgr; boundaries only inp‐type material. This indicates for &agr; dislocations donor behavior inp‐type material, acceptor behavior inn‐type material and for &bgr;‐dislocations donor characteristics. A theoretical model for the boundary states is proposed.