Aims: To examine the Campylobacter genotypes colonizing a litter of piglets during the first 10 weeks of life and compare them with those of the sow. Methods and Results: Campylobacters were isolated by direct plating of anal swabs. Piglets (n = 6) were sampled six times and five isolates per piglet obtained each time. The sow was also sampled but 20 isolates per sampling obtained. Isolates were genotyped by random amplification of polymorphic DNA, pulsed field gel electrophoresis and polymerase chain reaction/restriction fragment length polymorphism of the flagellin gene. Initially piglets were colonized by Campylobacter coli genotypes from the mother but after 66 days 33% of piglet isolates (based on a mean of the three-genotyping methods) were from other sources. The sow died after 14 days and the initial Campylobacter flora of the foster sow was subsequently replaced by genotypes from the piglets mother. However these constituted only a minor part of her flora after 52 days. Both foster sow and piglets carried multiple genotypes of Camp. coli: up to four in a single piglet sample and seven in one from the sow. Significance and Impact of the Study: Piglets are initially colonized by Camp. coli genotypes from their mother but later other genotypes displace them. Colonization is dynamic with the sow able to acquire genotypes from the piglets. Conclusions: The large numbers of Camp. coli genotypes carried by pigs, and frequent successions of dominant types, will render epidemiological studies problematic.