Proliferative colitis associated with intracellular Campylobacter sp was diagnosed in 10 ferrets. The ferrets had a history of diarrhea (often blood-tinged or mucoid), dehydration, and chronic weight loss. Additional clinical signs included rectal prolapse, lethargy, fever, and a palpably thick colon. In 5 ferrets, the diagnosis was confirmed by colonic biopsy, via endoscopy. Supportive treatment in 5 ferrets did not alleviate the clinical signs or the proliferative intestinal disorder. oral chloramphenicol treatment (50 mg/kg of body weight, q 12 h for 10 to 21 days) resulted in marked clinical improvement and eradication of proliferative intestinal lesions in 5 ferrets.