Objective: To evaluate the efficacy of lincomycin (Lincomix 20 Feed Medication; Pharmacia Animal Health, Kalamazoo, Michigan) at 44 and 110 ppm administered in feed for control of porcine proliferative enteropathy (PPE) in swine challenged with mucosal homogenate. Methods: A total of 312 commercial crossbred pigs at two sites were randomly assigned to receive lincomycin in feed at either 44 or 110 ppm, or no treatment. On 2 consecutive days, each pig was inoculated orally with Lawsonia intracellularis in the form of porcine intestinal mucosal homogenate. Animals were observed until clinical signs of disease were seen, then pigs assignedto treatment groups received lincomycin in the feed daily for 21 days. Control animals received no treatment. Clinical observations and performance were assessed throughout the study. Necropsies were conducted at the end of the study or at death. Results: The L intracellularis challenge produced a high incidence of clinical disease. The incidence of diarrhea and scores for abnormal clinical impression were lower and ADG and feed conversion efficiency were better in groups treated with either dose of lincomycin than in untreated controls. Mortality was lower in the group treated with lincomycin at 110 ppm than in the untreated controls. Implications: Under the conditions of this study, lincomycin administered in feed at 44 and 110 ppm for 21 consecutive days was effective in controlling clinical signs of PPE, and at 110 ppm also reduced mortality associated with PPE.