Microcrystalline cellulose (MCC) exhibits unusual tableting properties, sometimes, inconsistent with its high plasticity. It is found that some of the unusual tableting properties of MCC can be explained in part by the use of inaccurate true density during tableting data analysis. MCC true density as a function of water content is determined using a published method that can determine true density of water containing solids. Results suggest that literature MCC true densities tend to be overestimated as a result of limitations in helium pycnometry.