To define the species of Campylobacter harboring in the intestine of calves and adult cattle and to examine their distribution among different age groups and farms, 34 calves and 60 adult cattle raised in 6 farms in 3 different areas were studied. Campylobacters were detected in the feces obtained from healthy calves (97.1%) less than 1-year-old but were much less frequently found in adult cattle (46.7%). Young calves harbored more species of Campylobacter than adult cattle. The isolation rate of campylobacters in adult cattle differed depending upon the farms examined. C. jejuni, C. hyointestinalis and C. fetus subsp. fetus were isolated from 61.8, 26.5, and 26.5% of calves, respectively. However, these 3 species were detected at the lower rates of 11.7 to 15.0% in adult cattle. C. coli, C. lari, C. fetus subsp. venerialis, C. fecalis, and other Campylobacter spp. were also detected in a few calves and adults. These results indicate that campylobacter colonization in the intestine is very common in young calves but not in adult cattle.