Some of the clinical studies of IBD involve MetaHIT industrial partners. We centered on the one that concerns the effect of probiotics on the stability of microbiota in the UC patients, thought to be lower than in the healthy individuals. The study involved 50 patients and 10 healthy controls. One group of patients consumed daily a fermented milk product containing probiotic strains for three months, while another group took a product without the strains for the same period of time. Stool samples were collected at the onset and the end of the study and analyzed by the high throughput DNA sequencing. A preliminary analysis of the fluctuation of the bacterial gene abundance showed the expected high stability among the healthy individuals and a significantly lower stability among the patients taking placebo. Very interestingly, the patients that consumed the probiotics had an improved stability, similar to that of the healthy individuals. A number of follow-up studies are planned at present, in close interaction with the MetaHIT project.