In the title salt, [Hg(NCS)(CH4N2S)3]Cl, the Hg(2+) ion is coordinated in a severely distorted tetra-hedral manner by three thio-urea groups and one thio-cyanate anion through their S atoms. The S-Hg-S angles vary widely from 87.39 (5) to 128.02 (4)°. Weak intra-molecular N-H⋯S hydrogen bonds are observed, which form S(6) ring motifs. In the crystal, the ions are linked by N-H⋯N and weak N-H⋯Cl inter-actions, generating a three-dimensional network.