The theory of the rotational motion of slender particles subjected to Brownian couples is examined on the basis of two different sets of assumptions. The first set, which models the stochastic couples by a smooth diffusive type of expression, is well established in practice. The second set, which uses the theory of Wiener processes, is equally well established in principle. For the problem used for illustration, the two sets of assumptions are shown to yield the same results in an asymptotic sense as the inertia of the particle becomes progressively of relatively less importance.