The effects of perchloroethylene (PCE) concentration in the range of 0-100 mg/L on methane and acetate production by a methanol-enriched methanogenic consortia were investigated at 17 degrees C. The results indicate that PCE is more inhibitory to methanogenesis than to acetogenesis. At concentrations as low as 10 ppm, PCE affects the methanogenic activity of the consortium, and has completely inhibited this activity at 100 ppm. Conversely, PCE does not begin to inhibit acetogenic activity until the concentration is above 10 ppm, and has not completely inhibited it even at a PCE concentration of 100 ppm.