[Cronos]

I wonder what their reason is for being against blood transfusions?

The Freerepublic Jehovah's Witnesses can answer that

cyc -- any biblical reasoning for this?

[momtothree]

I looked up the answer on the JW website. It states that they follow Acts 15;20 and Acts 21;25 that essentially states “Christians must abstain from blood”. From the article, I got the impression the belief is that only God gives blood and man cannot. They do accept blood alternatives.