Lawsonia intracellularis (LI) is the causative agent of porcine proliferative enteropathy1, a disease that is found with high prevalence in all countries with industrial pig production. The infection is known to cause disease in different age groups. In pigs between 6 to 20 weeks of age the endemic form called Porcine Intestinal Andenomatosis (PIA) is predominant. The clinical signs are diarrhoea, ill-thriftiness and wasting. The objective of this study was to estimate the impact of LI detected in faeces on Average Daily Gain (ADG) in grower-finisher pigs.