AbstractBy using two model proteins, glucose oxidase and lipase, we demonstrate that dry crystalline formulations are significantly more stable than their amorphous counterparts. The results of Fourier‐transform infrared spectroscopy indicate that crystalline proteins better maintain their native conformation in accelerated stability studies. The lower tendency of crystalline proteins to aggregate is confirmed by size‐exclusion chromatography. The data suggest that protein crystallization may significantly improve some aspects of protein handling, and change the way biopharmaceuticals are produced, formulated, and delivered. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 358–369, 2001.