Yersinia enterocolitica was isolated from 10 of 121 soil samples from an area inhabited by infected wapiti (Cervus elaphus roosevelti) in northwest California. Significantly (p<0.05) more soil samples from a forest habitat were infected, compared to soil samples from prairie habitats. Soil was found infected with yersiniae only on dates for which rainfall in excess of 17 mm had occurred during the previous 7 days.