Abstract: A method for bulk cryopreservation of biological material includes the steps of providing a flexible container, such as a freezer bag, containing biological material that is treated with a cryoprotectant and freezing the biological material to below -100.degree. C. and preferably below -196.degree. C. for deep freeze long-term storage. In the preferred embodiment, the bag is placed in a holder that maintains the cross-sectional area of the bag essentially constant and small enough (e.g., about 5 mm width to facilitate uniform heat transfer to and from all regions the bag. This facilitates uniform nucleation of the biological material after supercooling which enables controlled and uniform slow cooling through from about -7.5.degree. C. to a temperature in the range of about -40.degree. C. to -80.degree. C., thereby maintaining the viability of the cells.