Abstract. We study the C 4 smooth convex bodies K ⊂ R n+1 satisfying K(x) = u(x) 1−p , where x ∈ S n , K is the Gauss curvature of ∂K, u is the support function of K, and p is a constant. In the case of n = 2, either when p ∈ [−1, 0] or when p ∈ (0, 1) in addition to a pinching condition, we show that K must be the unit ball. This partially answers a conjecture of Lutwak, Yang, and Zhang about the uniqueness of the Lp-Minkowski problem in R 3 . Moreover, we give an explicit pinching constant depending only on p when p ∈ (0, 1).