A simple theoretical method of studying the effect of weak anisotropy on the freezing of classical fluids is discussed. Free energy of the solid phase is separated into contributions due to the formation of the regular lattice and the remaining orientational part. The former is calculated by the density-functional theory, while a mean-field theory of orientational order is developed for the latter. An application to the freezing of hard dumbbell fluids yields results in good agreement with simulations.