A brief presentation of biogas production by anaerobic digestion of biodegradable organic waste and energy crops is given. Metabolic pathways of methane synthesis are outlined and diifferet process designs described. Data for the recovery of methane from different substrates are presented and some advantages of biogas development in the third World listed. The potential energy contribution would be significant if the major kinds of biodegradable organic waste and some energy crops were anaerobically treated. In the future it might even be profitable to use methane produced by anaerobic digestion as a raw material for chemical manufacture.