The crystal structure of the title compound, has been determined by single crystalX-ray diffraction by conventional heavy-atom methods. The structure was refined by block-diagonal least-squares procedures to a final R of 0籲 for 810 visually estimated reflections. Crystals are monoclinic, P21/a, a= 11縶1 (8), b= 15簲(1), c= 4緵1 (4)Ŭ = 106糰(6)ଠZ= 2. The centrosymmetric mercury atoms have three pairs of sulphur contacts in a highly distorted array, one pair close [Hg-S 2糹7(6)ŝ, and the others arising out of a sharing of the second sulphur between adjacent mercury atoms [Hg-S 2繹0(7), Hg-S 3糰7(7)ŝ yielding a helical quasi-polymeric array. The asymmetric co-ordination of the ligand is reflected in associated distortion of the CS2 geometry [C-S, 1綹(2) 1緶(2)Ŭ S-C-S 120(1)ݮ The remainder of the ligand geometry is normal.