A method for sterilizing products to inactivate biological contaminants such as viruses, bacteria, yeasts, molds, mycoplasmas and parasites is disclosed. The method involves irradiating the product at a low dose rate from about 0.1 kGy/hr. to about 3.0 kGy/hr. for a period of time sufficient to sterilize the product. The method does not destroy sensitive materials such as blood and blood components. Further, the method does not require pre-treatment of the product such as freezing, filtration or the addition of chemical sensitizers.