While the precise pathophysiology of IBS remains to be elucidated, dysmotility and altered visceral perception/sensation are currently the most popular hypotheses. More recently, roles for enteric infection and intestinal inflammation have been proposed. Probiotics, defined as live or attenuated bacteria or bacterial products that confer a significant health benefit to the host, have the potential to provide a clinical tool to explore these interactions. We reviewed the effects of probiotics on IBS symptoms.