This study investigated the removal of heavy metals by biological sulfate reduction using CO as the sole carbon and energy source. The effect of different heavy metals, viz. Cu, Zn, Cd and Pb at initial concentrations in the range 5-100 mg/L on their respective removal was studied. Maximum removal efficiency was obtained with Cu as sulfate reduction was mostly unaffected in the presence of this metal; more than 60% sulfate reduction could be achieved even at a high metal concentration of 100 mg/L of Cu. Among these metals, Pb showed very strong inhibitory effect on sulfate reduction and CO utilization by the anaerobic biomass. Thus, heavy metal removal by sulfate reduction in turn depended on CO utilization efficiency by the anaerobic biomass. Field-emission scanning electron microscopy microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX) and fourier transform infrared spectroscopy (FTIR) spectra of the metal containing biomass confirmed that the bioprecipitates produced during the experimental study primarily consisted of the metal sulfides. This study has significant implications towards biological treatment of sulfate rich heavy metal containing wastewaters using CO as the carbon and energy source.