Abstract: A method for sterilizing products to remove biological contaminants such as viruses, bacteria, yeasts, molds, mycoplasmas and parasites is disclosed. The method involves providing the product in a form that contains less than 20% solids and subsequently irradiating the product with gamma irradiation over an extended period of time. Generally the product is irradiated for a period of not less than 10 hours. The extended irradiation time in conjunction with the low level of solids in the product substantially reduces the damage to the product. The method is useful in sterilizing sensitive materials such as blood and blood components.