Q1:
Is it permissible for me to donate blood knowing that it may go to non muslims?
A: Yes, it is permissible.
Q2:
I wanted to know if giving blood is haram? if not is it a good deed?
A: Yes, it is permissible to give blood and donate it. It is some sort of charity and an expression of high morality. It is a good deed if the said was intended.
