Microbial control of the geochemical behavior of heavy metals and As in contaminated subsurface was investigated through activation of indigenous bacteria by organic supply under anaerobic condition. The results indicated that dissolved Cd, Pb and Zn were microbially removed from solutions, which was likely due to the formation of metal sulfides after reduction of natural sulfate by indigenous sulfate-reducing bacteria. The soil containing a large amount of sulfate resulted in complete removal of dissolved As after 25 days, while there were gradual increases in dissolved As concentration in the soils which showed low sulfate concentrations. Subsequent experiments with sulfate supply were conducted to identify the effects of sulfate amendment to stimulate microbial sulfate reduction on heavy metal behaviors. Batch-type experiments were performed with lactate or glucose as a carbon source to activate indigenous bacteria under anaerobic condition for 100 days. Sulfate (250 mg/L) was artificially injected at 60 days after the onset of the experiments. Lactate supply exerted no significant difference on the amounts of dissolved Zn, Pb, Ni and Cu between microbial and abiotic control slurries; however, lower Zn, Pb and Ni and higher Cu concentrations were observed in the microbial slurries than in the controls when glucose supplied. Sulfate amendment led to dramatic decrease in dissolved Cr and maintenance of dissolved As, both of which had gradually increased over time till the sulfate injection. Black precipitates formed in solution after sulfate amendment, and violarite was found via XRD analysis in the microbial precipitates. Conceivably the mineral might be formed after Fe(III) reduction and microbial sulfate reduction with coprecipitation of heavy metals. The results suggested that heavy metals in subsurface may be stabilized in situ by microbial sulfate reduction, and natural attenuation of the contaminants can be effectively attained.