The aim of this study was to determine the microbiological quality of runoff from an urban area with different catchment land use flowing into the Cybina River in Poznań, Poland. Water samples were taken from October 2009 to March 2011 at five research stations situated at the outlets of sewers draining a road surface, a car park, and residential and industrial areas. Microbiological analyses included: total bacterial count at 22ºC and at 37ºC, coliform group and faecal coliform bacteria. In each sample the coliform group and faecal coliform bacteria, probably of animal origin, were present. MPN coliform group ranged from 48 to 24·10⁵ cells in 100 ml. The results indicated that quality of stormwater depended on such factors as duration of the rainless period, season, and size and state of the impervious area. High microbiological contamination betokens an adverse influence on the water quality of the Cybina, and therefore treatment of this sewage before the outlets to the receiver is necessary.