The number of human cases of enteritis caused by Campylobacter jejuni and C. coli is increasing in Denmark and other European countries. No systematic typing has earlier been performed on Campylobacter isolates of Danish origin. The primary purpose of this study was to provide a serotype distribution of Campylobacter isolates from Danish patients and the major food production animals. In addition, the occurrence of intestinal carriers of thermophilic campylobacters among these food production animals was examined. In a nationwide survey, the individual isolation rate was 36% for broiler chickens, 47% for cattle and 46% for swine when sampled at the slaughterhouse. C.jejuni accounted for 83-91% of the thermophilic Campylobacter spp. in broiler chickens and cattle, whereas 95% of the isolates from swine was C. coli. In human patients with Campylobacter enteritis, 94% of the isolates were C. jejuni and 6% were C. coli. Heat-stable serotyping (the 'Penner scheme') was performed on a total of 398 isolates from the four sources: human patients (n = 145), broiler chickens (n 94), (n = 111) and cattle (n = 48)). Among human isolates, serotype O:144, O:2 and the O:4-complex accounted for 62% of the C. jejuni isolates. These serotypes were also common in samples from broilers and cattle. In swine, C. coli O:30 and O:46 were most common. The serotype distribution of human clinical isolates showed large overlap with the serotype distribution of campylobacters in cattle and chickens, and on this basis both could be major sources of human campylobacteriosis.