A similarity analysis is made of the steady, two-dimensional, laminar boundary layer flow of non-Newtonian fluids. The important conclusion drawn from this analysis is that for non-Newtonian fluids of any model, similarity solutions exist only for the case of a wedge flow of 90 deg. The only limitation is that the stress and rate-of-strain can be related by an arbitrary continuous function. The result in this paper further extends a recent work by Lee and Ames [11]. Numerical solutions for the Powell-Eyring model are presented in dimensionless form as an engineering application of the theory.