Abstract: This invention relates to methods for isolating highly purified mixtures of natural Type I interferon from white blood cells. The invention also relates to highly-purified mixtures of Type I interferon which resemble natural Type I interferon in that the highly purified mixtures of natural Type I interferon includes at least 9 subtypes, i.e., alpha-1, alpha-2, alpha-5, alpha-7, alpha-8, alpha-10, alpha-14, alpha-21 and omega, giving rise to at least 16, and possibly 20 or more molecular species, including alpha-1a, alpha-1new, alpha-2a, alpha-2b, alpha-2c, alpha-5, alpha-5LG, alpha-7, alpha-8a, alpha-8c, alpha-10a, alpha-14a, alphal4-b, alpha 14-c, alpha-14LG, alpha-21a, alpha-21b, alpha-21c, omega and omega LG.