Organically high polluted waste water sets special claims for an economical purification and the process treatment. Up to now these waste waters are being purified by anaerobic processes with simultaneous biogas generation. The fourstep anaerobic degradation is influenced by a lot of important parameters. Extensive researchers in the field of anaerobic microbiology has improved the knowledge of the fundamental principles. Parallel the reactor technology is developed worldwide. In general it seems that the fixed-film-reactor with immobilized bacteria has the best future to purify organically high polluted industrial waste water with short retention times under stable operation conditions.