As a part of systematic investigation of biologically active compound, new azo dye ligand N-(4, 6-dimethylpyrimidin-2-yl)-4-((2-hydroxynaphthalen-1-yl) diazenyl) benzene sulfonamide has been synthesized by diazotization of 4-amino-N-(4, 6-dimethylpyrimidin-2-yl) benzenesulfonamide and coupled with coupling compound, naphthalen-2-ol. A new series of Ni (II), Cu (II), and Zn (II) complexes derived from this azo dye ligand (L) were synthesized. The structures of the ligand and metal complexes were confirmed by spectroscopic studies (elemental analysis, IR, 1H NMR and mass spectra). The azo dye and its complexes have been screened for their in vitro antimicrobial activities against some bacterial stains and fungal strains by disc diffusion method. The results showed that, the presence of... metal causes more inhibition. The anthelmentic activity of the ligand and its complexes against adult Indian earthworms, Pheretima postuma are also investigated.