Aims: To determine the frequency of coinfection with multiple strains in sporadic cases of human Campylobacter infection. Method and Results: During 1999 10 single colonies of Campylobacter were cultured from each of 53 positive faecal samples. Five isolates were taken from nonselective agar after passive filtration of faecal suspensions and five isolates were taken from selective agar plates. All isolates were sero- and phage typed and their antibiotic resistance determined. Pulsed-field gel electrophoresis and flagellin gene typing were performed on selected isolates. One patient was infected with Camp. coli, the remainder with strains of Camp. jejuni. The majority of patients was infected with a single strain of Campylobacter, but from each of four samples, 7.5%, two strains of Camp. jejuni, confirmed by molecular typing, were identified. Conclusions: Coinfection occurs in sporadic cases of campylobacteriosis. Significance and Impact of the Study: This study has implications in outbreak investigation when distinct strains have been isolated from epidemiologically related patients and/or the suspected source or vehicle.