Let F : M3↪R5 be an
embedding of an (oriented) Z2-homology 3-sphere M3 in R5. Then F bounds an
embedding of an oriented manifold W4 in R5. It is well known that the signature
σ(W4) of W4 is equal to the μ-invariant of M3 modulo 16. In this paper we
prove that σ(W4) itself completely determines the regular homotopy class of
F.