A quantitative assessment was performed on a serum enrichment medium for Campylobacter (Vibrio) fetus, to test its effectiveness as a transport medium. Abundant yields of C fetus were obtained with an inoculum size of 10(4), even after keeping the medium in air at 22 to 23 C for 4 days prior to incubation at 37 C under microaerophilic conditions. The organism could be isolated from the medium kept in air at 22 to 23 C for at least 2 days, with an inoculum as small as 100 organisms. It was concluded that this formulation comprises a convenient and effective transport medium for field use. Transit time should not exceed 3 days and, ideally, should be restricted to less than or equal to 2 days. At least duplicate vials of transport medium should be inoculated with each sample.