Growth morphologies of {1 0 1} faces of manganese mercury thiocyanate (MMTC) crystals have been investigated by atomic force microscopy (AFM). The growth sources appear in groups at the crystal edges. Almost all of the growth hillocks generated by either 2D nucleation or dislocations are elliptical in shape. Their cuspidate sides orientate to about < 1 1 3 > or < 1 1 4 > direction, which demonstrates the fast growth along these directions. It is consistent with the case that {1 1 3} and {1 1 4} faces never appear. A new kind of step bunch, namely local step bunch, is observed. Formation of such a step bunch is probably due to impurities adsorbed at the steps. (c) 2005 Elsevier B.V. All rights reserved.