The article presents effectiveness of sewage pollutants’ reduction in Sewage Treatment Plant „KUJAWY”. Treatment plant “KUJAWY” is meant to neutralise living sewage from Nowa Huta quarter for Krakow city. Capacity of the treatment plant is 80 000 m3*d-1. The research was carried out in the period from 01.04.2006 to 31.03.2007. Results’ analysis was performed on the basis of raw and treated sewage concentration. Three pollutants’ indexes from the basic group were analysed: BOD5, CODCr and total suspended solids and two indexes from the eutrophic group: general nitrogen and general phosphorus. Basing on the results’ analysis, mean effectiveness of BOD5 reduction was defined on the level of 98,5%, CODCr – 96,0%, total suspended solids– 98,2%, general nitrogen– 73,7% and general phosphorus – 91,4%.