To provide new information on the epidemiology and pathophysiology of human infection with Campylobacter fetus subsp. jejuni, we studied its survival in several milieus. Standard inocula of organisms were placed in hydrochloric acid, human bile and urine, bovine milk, or stream water and kept at 4, 25, or 37 degrees C; viable organisms were then counted. Stools from humans infected with Campylobacter were similarly tested. Survival in acid was pH and time dependent, with 7-log kill within 5 min in solutions at pH 2.3. Organisms multiplied in bile at 37 degrees C and survived for 2 months. Organisms survived better in feces, milk, water, and urine kept at 4 degrees C than they did in these milieus at 25 degrees C. Maximal viabilities of Campylobacter organisms kept at 4 degrees C were 3 weeks in feces, 3 weeks in milk, 4 weeks in water, and 5 weeks in urine. Study results suggest that when these milieus are contaminated with C. fetus subsp. jejuni, they may be significant environmental reservoirs.