Abstract. Let p be a prime integer and F a field of characteristic 0. Let X be the norm variety of a symbol in the Galois cohomology group H n+1 (F, µ ⊗n p ) (for some n ≥ 1), constructed in the proof of the Bloch-Kato conjecture. The main result of the paper affirms that the function field F (X) has the following property: for any equidimensional variety Y , the change of field homomorphism CH(Y ) → CH(Y F (X) ) of Chow groups with coefficients in integers localized at p is surjective in codimensions < (dim X)/(p−1). One of the main ingredients of the proof is a computation of Chow groups of a (generalized) Rost motive (a variant of the main result not relying on this is given in Appendix). Another important ingredient is A-triviality of X, the property saying that the degree homomorphism on CH 0 (X L ) is injective for any field extension L/F with X(L) = ∅. The proof involves the theory of rational correspondences, due to Markus Rost, reviewed in Appendix.