The results obtained in work carried out in order to verify the overall efficiency of full-scale, long-term, activated-sludge treatment of winery wastewater are presented. The analytical data showed the high removal of COD (average 98%; min. 97.6; max. 99.1) during the whole experimentation period and with various working parameters. The effluent had chemico-physical values in conformity with Table A of Italian Law No. 319 of 10 May 1976. Sludge production was lower than that produced by ordinary activated-sludge plants. Moreover, because of the low contents of heavy metals, organic matter and N, P, K content, this aerobic sludge is suitable for direct agricultural use or for compost production. The plant proved itself to be flexible enough to withstand large variations in the hydraulic and pollution loads and was found to have a low cunning cost.