General expressions for the changes in resistivity and conductivity around 60°, edge, and screw dislocations as a consequence of the piezoresistance effect were calculated for III‐V compounds. These expressions are discussed with reference to the symmetry of the crystal. The specific case ofn‐type GaSb is considered and it is shown that 60° and edge dislocations are surrounded by regions of increased and decreased conductivity parallel to the lines of the dislocations. It is also shown that the conductivity parallel to the line of a screw dislocation is increased irrespective of the sign of the Burgers vector. The results indicate that the dislocations can alter the bulk conductivity parallel to their lines and that they can play an important role in the threshold behavior of laser devices. Finally, it is shown that there are charging effects associated with the dislocations during device operation.