The development of pulp and paper production and technology is reviewed with special emphasis on its influence on the waste water discharge. The chemical pulping methods are in a rapid development phase, including novel processes as well as substantial changes taking place in the kraft pulping process. Due to the changing chemical pulping and bleaching practice, the chlorinated organic compounds in the effluent will lose their importance. Research should be focused on the effects of new contaminants introduced in chlorine-free bleaching, and on the natural substances occurring in wood that are causing the remaining toxicity of the effluent from both mechanical and chemical pulp mills. Enhanced recycling of post-consumer paper and board leads to an increased number of deinking plants with new types of discharges. Closure of process water loops are also expected in the near future, which may totally eliminate the process water discharges from modern mills.