Abstract Magnetization steps due to nearest-neighbor Mn 2+ pairs in Cd 0.977Mn 0.023S and Zn 0.97Mn 0.03S are much narrower in pulsed fields than expected from thermal broadening, and show a fine structure. These narrow steps imply a pair spin-lattice relaxation time much longer than 0.5 ms. An interpretation of the narrow steps, based on the Dzyaloshinski-Moriya interaction, is proposed. The nearest-neighbor exchange constant J NN for (Zn,Mn)S is JNN kb = -16.9 0.6 K . The effects of polytypism of J NN in (Zn,Mn)S are discussed. For (Cd,Mn)S, JNN kB = -9.65 0.2 K and -11.0 0.2 K , corresponding to two inequivalent NN's in the wurtzite structure.