Abstract. Let QC(K, g) be a family of K-quasiconformal mappings of the open unit disk onto itself satisfying the PDE Δw = g, g ∈ C(U), w(0) = 0. It is proved that QC(K, g) is a uniformly Lipschitz family. Moreover, if |g| ∞ is small enough, then the family is uniformly bi-Lipschitz. The estimations are asymptotically sharp as K → 1 and |g| ∞ → 0, so w ∈ QC(K, g) behaves almost like a rotation for sufficiently small K and |g| ∞ .