The atomic structures of dislocations in BaF2/CaF2 (111) multilayers grown on Al2O3 were studied by high-resolution transmission electron microscopy on ( ) and ( ) cross-sections. It was found that dislocations generated in these multilayers have structures significantly different from those observed in bulk materials, and that the dislocation structure depends on the morphology of the multilayer. Most dislocations are misfit dislocations along and have Burgers vectors of a/2 on the (111) interfaces. Interface dislocations with a Burgers vector of a/2⟨ 110 ⟩ on (11 ) planes are also observed in multilayers of medium layer thickness l with wavy interfaces. Occasionally, edge dislocations with Burgers vectors a/2⟨ 110 ⟩ and a/2⟨ 001 ⟩ are observed along [1 0]. Edge dislocations with Burgers vectors a/2[ 10] are found dissociated into two partials with an in-plane Burgers vector component of a/4[ 10], and form low-angle boundaries. The influence of these crystal defects on the chemistry of point defects in these multilayers must be taken into account when the ionic conductivity of the multilayer is predicted by space charge theory.