We investigate the existence and uniqueness of positive solutions of the following nonlinear fractional differential equation with integral boundary value conditions CDαu(t) + f(t, u(t)) = 0, 0 < t < 1, , where 2 < α < 3, 0 < λ < 2 and CDα is the Caputo fractional derivative and f : [0,1]×[0, ∞)→[0, ∞) is a continuous function. Our analysis relies on a fixed point theorem in partially ordered sets. Moreover, we compare our results with others that appear in the literature.