For shipment of biological substances on dry ice, the package must consist of three components: a primary receptacle (e.g. a cardboard cryogenic storage box with divider or similar device), a secondary package that includes absorbent material, and a rigid outer package such as an insulated, leak-proof, thermal shipping container. The sample tubes are placed inside the primary receptacle, the primary receptacle is placed inside the secondary package in such a way that, under normal conditions of transport, they cannot break, be punctured or leak their contents. If leakage does occur during transport, the absorbent material inside the secondary package will contain the spill. The secondary package is placed into the leak-proof shipping container and dry ice is placed around and above the secondary package.