Abstract. It is an interesting question how (analytic continuation of) quantum cohomology is related to birational geometry. In particular, we expect that quantum cohomology decomposes in a certain way for extremal contractions. In this talk, I will explain such a decomposition for blowups: quantum cohomology of the blowup of X along Z will decompose into QH(X) and (codim Z-1) copies of QH(Z). The idea of the proof comes from Teleman's conjecture on quantum cohomology of symplectic reductions.