Convergent beam electron diffraction using either the (200) systematic row and/or the (011) zone axis was successfully applied to determine the crystal polarity in (011) GaAs samples. This method makes it possible to distinguish the stacking sequence of the As and Ga planes. The information existing in the 200 disk of the diffraction pattern is different, depending on whether a particular disk refers to the As or the Ga plane. Therefore, this method can be generally applied in transmission electron microscopy forinsitusamples and without any chemical etching.