Aims: Yersinia enterocolitica causes several syndromes in humans. The most common presentation is enterocolitis in children, presenting as fever and diarrhoea. A Y. enterocolitica multiple strain infection in twin infants was investigated. Methods and Results: One isolate was recovered from one patient and two morphologically-different isolates were recovered from the other infant. Biochemically, all isolates were identified as Y. enterocolitica group. The genomic DNA from each strain was purified and DNA fingerprinting was performed. The banding patterns observed for Y. enterocolitica isolates 2 and 3, from patients 1 and 2, respectively, were identical when comparing the presence or absence of major bands. However, Y. enterocolitica isolate 1, from patient 1, showed a distinctive banding pattern from isolates 2 and 3. Conclusions: The findings indicate that one infant was colonized by more than one strain of Y. enterocolitica, demonstrating that multiple strains can colonize and invade a patient. Significance and Impact of the Study: Recognition of multiple strain infections can be important in diagnosis, treatment and prognosis of Y. enterocolitica infections, as well as in disease epidemiology. The technique described here offers a straightforward method for strain comparison.