NH4CuS4 was prepared according to syntheses reported in the literature. Orthorhombic crystals could be grown (P212121, a = 5.249(1), b = 8.444(2), c = 12.782(2) Å , Z = 4), the structure of which was solved from X-ray diffractometer data (R = 0.031 for 767 obs. reflections). In the solid state (CuS4)--chelate rings are linked via additional Cu-S-bonds to form one-dimensional polymeric anions.