Abstract: A process for the freezing of organic tissue is disclosed, in which the atmospheric pressure in contact with the tissue is gradually lowered before or during the freezing process. The decompression is done at a rate and to a degree whereby a substantial portion of the gaseous matter dissolved in the cellular fluid is released to the atmosphere, without substantial vaporization of the fluid itself. The release of the dissolved gases permits freezing of the tissue without damage to the cellular structure, and thus permits a full return to the original appearance and consistency upon thawing.