Uv-visible spectrophotometry, flame atomic absorpti on spectrophotometry and HPLC techniques have been developed for the assay of metronidazole in bulk dr ug and in dosage forms via complex formation with A u(III) and Hg(II) ions in solutions after fixing maximum react ion conditions . In the first two techniques, chlor oform was used as a solvent for the two complexes with extraction percentages (96.652,93.975%) respectively. Stabil ity constants for the two extracted complexes were (1.697x10 4 , 5.118x10 5 )respectively. Beer's law was obeyed for (5-55), ( 2- 22μ g/ml) for uv-visible and atomic spectrophotometr ic methods respectively. The HPLC determination for metronidazole and its complexes was performed simul taneously without extraction or separation step wit h peak absorption at λ (272nm), (280nm) for Au and Hg complexes respective ly. A rectilinear relationship between two mean peaks area for metronidazole and its complexes with concentrations was observed in the range (10- 110 μ g/ml). The correlation coefficients, regression e quations, detection limits and recoveries for the t wo complexes in the three methods were calculated. These methods h ave been successfully applied to assay of metronida zole in preparations .