Aims: To use a published polymerase chain reaction (PCR) method for the detection and identification of thermotolerant Campylobacter species (Camp. jejuni, Camp. coli and Camp. lari) in tandem with a Most Probable Number (MPN) technique to enumerate these species in water samples. Methods and Results: An initial study of 42 river water samples compared the use of conventional culture and PCR methods for the detection of Campylobacter in MPN enrichment tubes. It was found that all samples positive by culture were also positive bit PCR. Thirty-seven percent more MPN tubes were positive by PCR compared with culture. The MPN/PCR technique nias subsequently applied to 96 additional samples collected fi om rivers, drinking, roof and shallow ground water. Campylobacter was especially prevalent in river water (60% positive) and shallow ground n ater (75% positive) samples. Drinking water (29.2% positive) and roof water (37.5% positive) also contained Campylobacter, but the numbers detected were very low (maximum 0.3 and 0.56 MPN 100 ml(-1), respectively). Conclusions: River waters contained Campylobacter at higher levels than any other water type and in a high percentage of the samples. Although Campylobacter was present in treated drinking water, the levels detected were low. Significance and Impact of the Study: These results suggest that water may act as a significant transmission route for human campylobacteriosis.