This thesis presents the prevalence estimation of porcine proliferative enteropathy (PPE) at the individual and herd level in Ontario's pig farms by means of serologic tests. It also examines the relationship between within-herd prevalence of PPE and biosecurity measures in high health herds. A comparison of results from two different serologic tests for PPE was also performed. PPE was shown to be a widespread disease in commercial and high health herds in the province of Ontario. PPE within-herd prevalence had no relationship with biosecurity measures. Factors such as farm type and finisher barn flow were associated with seropositivity, whereas inclusion of in-feed antibiotics was negatively associated. The agreement between serologic tests at the individual level was poor while the agreement of the tests at the herd level was moderate.