Let g(t) be a complete solution to the Ricci flow on a noncompact manifold such that g(0) is Kähler . We prove that if |Rm(g(t))| g(t) ≤ a/t for some a > 0, then g(t) is Kähler for t > 0. We prove that there is a constant a(n) > 0 depending only on n such that the following is true: Suppose g(t) is a complete solution to the Kähler-Ricci flow on a noncompact n-dimensional complex manifold such that g(0) has nonnegative holomorphic bisectional curvature and such that |Rm(g(t))| g(t) ≤ a(n)/t, then g(t) has nonnegative holomorphic bisectional curvature for t > 0. These generalize the results in [21]. As corollaries, we prove that (i) any complete noncompact Kähler manifold with nonnegative complex sectional curvature with maximum volume growth is biholomorphic to C n ; and (ii) there is ǫ(n) > 0 depending only on n such that if (M n , g 0 ) is a complete noncompact Kähler manifold of complex dimension n with nonnegative holomorphic bisectional curvature and maximum volume growth and if (1 + ǫ(n)) −1 h ≤ g 0 ≤ (1 + ǫ(n))h for some Riemannian metric h with bounded curvature, then M is biholomorphic to C n .