This paper concerns matrix "convex" functions of (free) noncommuting variables, . It was shown in Helton and McCullough (SIAM J Matrix Anal Appl 25(4):1124-1139, 2004) that a polynomial in which is matrix convex is of degree two or less. We prove a more general result: that a function of that is matrix convex near and also that is "analytic" in some neighborhood of the set of all self-adjoint matrix tuples is in fact a polynomial of degree two or less. More generally, we prove that a function in two classes of noncommuting variables, and that is both"analytic" and matrix convex in on a "noncommutative open set" in is a polynomial of degree two or less.