Vaccinations were originally acceptable.
1921 - In 1921 Witnesses were forbidden vaccinations (Golden Age 1921 October 12 p.17)
1952 - After 30 years the Watchtower Society returned to its original position, once again allowing vaccinations. (Watchtower 1952 December 15 p.764)
Organ transplants were originally considered "wonders of modern surgery." (Awake! 1949 December 22)
1967 - Transplants forbidden to Witnesses as cannibalism. This continued to be the case through the 1970's. (Watchtower 1967 Nov 15 pp.702-704)
1980 - The Society overturned the decision and transplants became acceptable once again. (Watchtower 1980 Mar 15 p.31)
Initially blood could be eaten. (Watchtower 1892 Nov 15 pp.349-352, Watchtower 1909 Apr 15 pp.116-117)
1927 - Blood was no longer to be eaten (Watchtower 1927 December p.371)
1954 - Unacceptable.
"We are told that it takes one and a third pints of whole blood to get enough of the blood protein or "fraction" known as gamma globulin for one injection... its being made of whole blood places it in the same category as blood transfusions as far as Jehovah's prohibition of taking blood into the system is concerned." Awake! 1954 Jan 8 p.24
1958 - Acceptable (Watchtower 1958 Sep 15 p.575)
1963 - Unacceptable (Watchtower 1963 Feb 15 p.124)
1965 - Acceptable (Watchtower 1964 Nov 15 pp.680-3)
1974 - Conscience matter (Watchtower 1974 Jun 1 p.352)
1972 - Unacceptable.
"The Journal of the American Medical Association, dated Nov 15, 1971, described a procedure for open-heart surgery that employs "sever hemodilution." Early in the operation a large quantity of blood is drawn off into a plastic blood bag. Though the bag is left connected to the patient by a tube, the removed and stored blood is no longer circulating in the patient's system. It is replaced with a plasma volume expander, which dilutes the blood remaining in the veins and which gradually dissipates during the operative procedure. Near the conclusion of the operation the blood storage bag is elevated, and the stored blood is reinfused into the patient. The New York Times of Nov 9, 1971, reported on a somewhat similar procedure whereby some days before one undergoes surgery as much as four pints of blood are removed and stored. During the operation the person's own stored blood is transfused back into him, thus avoiding the danger of disease and mismatched blood. These techniques are noteworthy to Christians, since they run counter to God's Word. The Bible shows that blood is not to be taken out of a body, stored and then later reused." Awake! 1972 Apr 8 p.30
1982 - Objectionable.
"Techniques for intraoperative collection or hemodilution that involve blood storage are objectionable to them." Awake! 1982 Jun 22 p.25
1983 - Acceptable.
"It is with this in mind, and not just to honor the requests of Jehovah's Witnesses, that Denton Cooley [of Houston, Texas] has performed open-heart operations now for over seven years, limiting transfusions wherever possible by substituting hemodilution, diluting the patient's blood with a glucose and heparin solution." Awake! 1983 Mar 22 p.16
Originally Allowed. Blood transfusions and donating blood for transfusion is commended (Golden Age 1925 July 29 p.683, Golden Age 1929 May 1 p.502, Consolation 1940 December 25 p.19)
1945 - Forbidden. Blood transfusions first stated as wrong (Watchtower 1945 July 1 p.198-201)
1961 - Became a disfellowshipping offence (Watchtower 1961 Jan 15 pp.63-64)
In 1961 it was clearly specified that blood law applies to both whole blood and components of blood such as blood fractions and haemoglobin.
"If you have reason to believe that a certain product contains blood or a blood fraction if the label says that certain tablets contain hemoglobin this is from blood...a Christian knows, without asking, that he should avoid such a preparation. Watchtower 1961 Nov 1 p.669
Gradually becoming allowed again
1982 - Blood components are listed with some minor components allowed. Major components and hemodilution are forbidden. (Awake! 1982 Jun 22 p.25)
1995 - Acute Normovolemic Hemodilution (ANH) and autologous blood salvage procedure (Cell Saver) are acceptable despite being briefly stored outside the blood. (Watchtower 1995 August 1 p.30)
2000 - Major change to blood policy, with all of blood now being allowed when converted to minor fractions.
"...when it comes to fractions of any of the primary components, each Christian, after careful and prayerful meditation, must conscientiously decide for himself." Watchtower 2000 Jun 15 pp.29-31
2004 - Hemoglobin, a major component of blood by weight is specifically permitted - In the Watchtower 2004 June 15 it is shown graphically that transfusions of whole blood and transfusions of the 'major' components of blood are forbidden. 'Major' components are stated to be red cells, white cells, plasma and platelets. However, fractions of these four components may be used. In other words, when blood is broken down into small enough components 100% of it can be transfused by a Jehovah's Witness.