In this communication, results are presented of the application of etching in molten E+M etch (KOH-NaOH eutectic mixture with 10% MgO) for studying defects in GaN. The method was used to study defects on differently oriented cleavage and basal planes of GaN single crystals, MOCVD-, MBE- and HVPE-grown epitaxial layers and LD and LED structures. Dislocations, dislocation loops and stacking faults have been revealed on $(10\, \bar{\text{\scriptsize 1}}\, 0)$, $(1\,\bar{\text{\scriptsize 2}}\,10)$ and $\{0001\}$ Ga- and N-polar planes. Diversified etch pit morphology was observed depending on the crystallographic orientation of the etched samples and was correlated with the crystallographic symmetry of the GaN lattice. Etching results were calibrated using TEM analysis.