I believe there has been one clinical trial re VSL3 which indicated some promising results. There have been some other studies re probiotics in general that have shown conflicting results -- some showed improvement in some patients, others not so much. Overall I think the scientific verdictis still out, but you see a lot of anecdotal comments on this forum and elsewhere that indicate in general that they sure can't hurt, and may help many patients, at least in some marginal ways.