Eldorado Resources was formed in 1926 in Canada originally as Eldorado Gold Mines, primarily mining gold. However, in 1930, after finding radioactive deposits at Great Bear Lake, Northwest Territories, the company transitioned to mining primarily radioactive materials and changed its name to Eldorado Nuclear Limited to reflect this. It was nationalised in 1943 and owned by the Canadian government.

In 1988 it was merged with Saskatchewan Mining Development Corporation to form the Cameco Corporation.

They were headquartered in Port Hope, Ontario, Canada.