In different countries numerous people have suffered from many infections caused by Escherichia coli O157:H7 within the last 20 years. This bacterium has been found in healthy bovine faeces. Therefore milk and milk products produced from such animals' milk may cause an infection risk if the milk has not been adequate pasteurised. In this research, 100 raw milk samples from different bovines and 50 white pickled cheeses manufactured from raw milk were examined for the presence of E. coli O157. Furthermore some physical and chemical properties were investigated. According to the analysis results, E. coli O157 was determined in 1% of the total raw milk samples and in 4% of the cheese samples. pH values were found to be higher than 4.50 in 80% of the total cheese samples. The main reason was that no lactic starters were used in this kind of cheese manufacturing process. Due to the low acidity of the cheese samples, E. coli O157 counts may increase and its survival time may be longer than in cheeses made using starter cultures. Thus, white pickled cheeses manufactured from unpasteurised milk have a potential infection risk as a result of E. coli O157 existence. (C) 2003 Elsevier Ltd. All rights reserved.