Anaerobic treatment is often reported to be an effective method for treating dairy effluents. The objective of this paper is to summarize recent research efforts and case studies in anaerobic treatment of dairy wastewaters. The main characteristics of industrial dairy waste streams are identified and the anaerobic degradation mechanisms of the primary constituents in dairy wastewaters, namely carbohydrates (mainly lactose), proteins and lipids are described. Primary attention is then focused on bench-pilot-full-scale anaerobic treatment efforts for dairy waste effluents. Combined (anaerobic-aerobic) treatment methods are also discussed. Finally, areas where further research and attention are required are identified. 2005 Elsevier Ltd. All rights reserved.