Three-dimensional imaging of protein crystals during x-ray diffraction experiments opens up a range of possibilities for optimizing crystal quality and gaining new insights into the fundamental processes that drive radiation damage. Obtaining this information at the appropriate length-scales however is extremely challenging. One approach that has been recently demonstrated as a promising avenue for characterizing the size and shape of protein crystals at nanometre length-scales is Bragg coherent diffractive imaging (BCDI). BCDI is a recently developed technique that is able to recover the phase of the continuous diffraction intensity signal around individual Bragg peaks. When data is collected at multiple points on a rocking curve, a reciprocal space map (RSM) can be assembled and then inverted using BCDI to obtain a three-dimensional image of the crystal. The first demonstration of two-dimensional biological BCDI was reported by Boutet et al on holoferritin, recently this work was extended to the study of radiation damage in micron-sized protein crystals. Here we present the first three-dimensional reconstructions of a Lysozyme protein crystal using BDI. The results are validated against RSM and transmission electron microscopy data and have implications for both radiation damage studies and for developing new approaches for structure retrieval from micron-sized protein crystals.