The limits of the parent grain reconstruction by the neighbor-to-neighbor method are shown. A new method of parent grain reconstruction from EBSD data is proposed for any phase transformation. It is based on the theoretical groupoid structure formed by the variants and their operators. It tolerates materials with high levels of intragranular deformation. It is quick and robust because it does not imply solving any equation, and mainly consists in the comparison of numbers. It has satisfactorily been applied to the reconstruction of austenitic grains in martensitic steels. © 2006 Elsevier Inc. All rights reserved.