The method involves (a) freezing fresh frozen plasma from a single donor, e.g. a human or other animal such as a cow, pig or sheep, which has been screened for blood transmitted diseases, e.g. one or more of syphilis, hepatitis or acquired immune deficiency syndrome at about -80??? C. for at least about 6 hours, preferably for at least about 12 hours; (b) raising the temperature of the frozen plas