ABSTRACTTwo methods for the strain tensor analysis of crystals will be presented. One of them is based on a modified x-ray back-reflection divergent (BDB) method. By the interposition of a wire grid between crystal and film, a computer-aided ray tracing technique was developed resulting in simultaneous precision measurements of d-spacings of several (hkl) planes. The strain input data for the tensor analysis are = (dn-dn°)/dn°, where dn° is the d value of the corresponding unstrained (hkl) planes, the precision of the strain measurements being ± 0.02%. The strain tensor εij obtained from the strain components, referred to the cubic coordinate system, is calculated by a least square method and the principal strains and their directions are determined. From the principal strains and known elastic constants the complete stress-strain configuration as well as the stored elastic energy are determined. An example of application to the elucidation of strains in premartensitic Al Ni crystals will be given. The other x-ray method presented is based on a computer-aided rocking curve analysis (CARCA) method, which is particularly well suited for the tensor analysis of non-uniform strain distribution in epitaxially grown microelectronic materials. This method determines not only the full elastic strain tensor, but also its distribution about a strain center with a resolution of approximately 60 Pm. As an example the strain distribution in an InGaAsP epitaxial film on an InP substrate is presented.