Samples of sphalerites from various deposits exhibited lattice defects, as detected using transmission electron microscopy. In a weakly-deformed specimen, extended dislocations with stacking-fault energies ranging from 4 to 8mJ/m2 were observed. Sphalerite deformed plastically by slip on (111)<110> and/or by twinning on (111) and it was not possible to specify the relative contributions made by these two mechanisms. The transmission electron microscopy observations were consistent with the geological history of the specimens. Observation par Microscopie Electronique en Transmission d'Echantillons de Blende de Diverses Provenances. J.J.Couderc, I.Dudouit, J.Bras, M.Fagot: Bulletin de Mineralogie, 1983, 106[4], 369-81