The ‘differential method’ of the interpretation of steady-state space-charge-limited (SCL) currents has been employed to critically check the validity of the analytical equations, previously described in the literature, describing SCL current-voltage characteristics. Equations derived for SCLC controlled by a monoenergetic trapping level, as well as by exponential and Gaussian distributions of traps have been taken into account. It was concluded that the analytical equations can be employed to fit experimental data only sufficiently far from trap-filled-limit voltages.