These preliminary results compare the on-farm prevalence and frequency of carcass contamination with Yersinia enterocolitica (YE) for pigs reared under conventional and antibiotic free production systems. At the time of submission, results are available for 6 herds. In 5 of 6 herds, we were able to isolate YE from at least one pig on-farm. The overall individual pig prevalence was 13.3% on conventional farms 59.3% on ABF farms. YE was isolated from 2 of 191 carcass swabs. Although the preliminary nature of these results limits interpretation, it supports previous results that indicate swine serve as a reservoir for YE.