According to the Montreal Gazette, Steinman died on Friday of pancreatic cancer.
"It is with deep sadness and regret that the Nobel Assembly at Karolinska Institutet has learned that Professor Ralph Steinman, one of this year´s three Nobel Laureates in Physiology or Medicine, passed away on September 30th," the Nobel committee said in a statement released Monday afternoon.
The committee explained it had received word of Steinman's death at 2.30pm CET from the president of Rockefeller University, after the announcement that he had been awarded the 2011 Nobel for medicine.
"Our thoughts are with Ralph Steinman's family and colleagues," the committee added.
Nobel Prize regulations prohibit the award being given posthumously, although it remains unclear how Steinman's situation would be handled.
"All we can do now is express our regret that he didn't get to experience the joy for his discoveries," Nobel committee secretary Göran Hansson told the TT news agency.
"We're examining the rules. In principle, you can't reward the deceased. This is a very unique situation because he died hours before the decision was made."
Hansson added, however, that there are no plans to over Steinman's share of the prize to someone else.
In a statement on the Rockefeller University website, Steinman's daughter expressed the family's gratitude over her father's Nobel Prize.
“We are all so touched that our father's many years of hard work are being recognized with a Nobel Prize,” said Alexis Steinman.
“He devoted his life to his work and his family, and he would be truly honored.”
Despite the regulations, there is precedent with two individuals who died in the months between their nomination and the decision of the prize committee rendered eligible to receive the prize.
This situation has occurred twice with the 1931 Literature Prize awarded to Erik Axel Karlfeldt, and the 1961 Peace Prize awarded to UN Secretary General Dag Hammarskjöld.
Since 1974 the requirement has been that laureates must be alive at the time of the October announcement.
There has been one laureate, William Vickrey, who died three days after he learned that he had won the 1996 Nobel Memorial Prize in Economics but before it could be presented. In this instance the prize was accepted on his behalf by a colleague at Columbia University.