Ferroelectric materials, such as BaTiO3, have piezoelectric properties that make them attractive for microelectronic and sensing applications(1). It is well known that the application of mechanical stress or electric field can alter the domain structure in ferroelectrics(1-6). Indeed, the constitutive behaviour of a ferroelectric is largely governed by the formation, movement and interaction of its domains. Therefore, it is crucial that the micromechanics of domains and their effect on internal stresses in ferroelectrics be understood. Here we show that the emerging technique of scanning X-ray microdiffraction(7) can be used to measure directly, for the first time, the local triaxial strain fields around 90degrees domains in single-crystal BaTiO3. Specifically, residual strain maps in a region surrounding an isolated, approximately 40 mum wide, 90degrees domain were obtained with 3 mum resolution, revealing significant residual strains. This information is critical for accurate micromechanical modelling of domain behaviour in ferroelectrics.