Soil remediation of organic and inorganic-combined contaminations has been reported in many parts of the world. Contaminants in co-contamination include MTBE, TCE, diesel, heavy metals, and so on. Previous biodegradation studies reported significant difference in single and co-contamination. Some reported a synergistic effect on cytotoxicity, and the components of contamination affected degradation differently. However, many results indicated that heavy metals inhibited biodegradation of organic pollutant. In addition, metals affected degradation rates in many studies. Most of these researches were carried out in artificial conditions. So, we are in need of more-close-to-field data. We extracted indigenous microorganisms from actual site that was contaminated with lead, zinc, BTEX, and TPH. Then, lead, copper, chromium, and diesel were added in order to see the effect of these contaminants on the biodegradation of organic compounds under anaerobic condition. Soil samples were collected from a co-contaminated site at different depths. The soil was passed through 2mm sieve. Indigenous bacteria were extracted from the soil using NB medium. Biodegradation was experimented in batch mode in 200 ml BS medium. The 250mL bottles were mechanically mixed in the dark at 30℃ after nitrogen purging in the liquid phase. TPH was analyzed using GC/FID. We will also perform the AMES test for general that is to assess the mutagenic potential of chemical compounds.