A methodology that directly images the full three-dimensional (3-D) shape of crystals within a crystallizer is reported. It is based on the mathematical principle that if the two-dimensional (2-D) images of an object are obtained from two or more different angles, the full 3-D crystal shape could be reconstructed. A prototype instrument is built and proof of concept study performed to demonstrate the potentials in using the system for 3-D measurement of crystal shape and shape distribution. It is our belief that 3-D measurement of crystal shape represents a significant step forward from existing work of 2-D measurement of crystal morphology and is potentially of great significance to research toward closed-loop control of crystal morphology. (C) 2015 American Institute of Chemical Engineers