Different preservation methods were evaluated for the storage of anaerobic sludges: room temperature, refrigeration at 4 degreesC, freezing at -20 degreesC and freeze-drying. Specific methanogenic activity for glucose and acetate were used as indicators of the subsequent recovery of the anaerobic sludge. Storage at room temperature and refrigeration resulted in a better conservation of the methanogenic activity than freezing and freeze-drying.