We describe structural analysis at the atomic level of InAs quantum dashes (Qdashes) grown on a GaAs substrate using an AlGaAsSb metamorphic buffer. Such characterization methods reveal the strain distribution within the quantum feature and provide insight into formation processes. The Qdashes are studied using high-resolution transmission electron microscopy that allows real-space measurement of the atomic lattice constant, a(0). The variation of the lattice constant is measured along both the [110] and the [1-10] directions in the asymmetric Qdash and indicates a highly tensile core surrounded by a compressively strained matrix. The study involves both capped and uncapped dashes to observe the effect of the encapsulating matrix on the lattice constants in the dash. (C) 2004 American Vacuum Society.