Structural and magnetic properties of nanocrystalline Fe0.67Co0.33 alloy prepared by high energy ball milling have been studied by x-ray diffraction and Mossbauer spectroscopy. The x-ray diffraction pattern of the sample milled for 160 hours indicates the existence of a single bcc phase. On the other hand, Mossbauer measurements, at different temperatures, show that the milled sample has two magnetic components with the same average hyperfine parameters. One sextet component is associated with large crystallites of bcc Fe0.67Co0.33 alloy, stable in vacuum up to 825 K and the other component is attributed to small crystallites of Fe0.67Co0.33, alloy having sizes in the range from 10 to 18 nm.