This paper presents a comparative study of aerobic and anaerobic bioremediation of 1,2-dichloroethene (DCE) and vinyl chloride (VC), and includes laboratory bench scale testing of anaerobic biodegradation and a side by side field pilot test comparing the effectiveness of aerobic and anaerobic biodegradation processes. Manufacturing activities at an industrial facility in Ohio resulted in trichloroethene (TCE) releases to the subsurface soil and groundwater. Most of the TCE source material was removed from the site through a soil remediation effort however dissolved phase contamination still remains in the groundwater. Sampling data indicate that the TCE has naturally degraded to its daughter products (DCE and VC), and little TCE still remains in the groundwater. Prior to initiating the pilot test, DCE and VC concentrations ranged from 220 to 5700 μg/L in the test wells.