In order to determine the cause of shrinkage, different factors were modified at each stage of lyophilization. It was determined that shrinkage of leather is due to accelerated drying happening at the same time as secondary desiccation. Leather dried in this way must recover an amount of moisture in order to return to its original dimensions; progressive rehumidification facilitates the phenomenon. However, for a degraded leather which is harder to put back into equilibrium with the surrounding relative humidity, the use of cryoprotectors may be appropriate.