Irritable bowel syndrome (IBS) is a complex multifactorial functional disorder, whose pathophysiology is largely associated to an impairment of the intestinal microbiota composition, namely dysbiosis. Thus, the modulation of the gut microbiota has been proposed as a possible therapeutic strategy for IBS patients alongside with current available drugs. Fecal microbiota transplantation (FMT) is a promising strategy to restore intestinal eubiosis. In this randomised double-blind placebo-controlled trial patients diagnosed with IBS without constipation are assigned with 1:1 ratio to receive FMT from healthy donor or autologous FMT (placebo group) to assess the effectiveness of FMT on IBS symptoms and quality of life, to evaluate the safety of FMT among IBS patients and to estimate any change in the gut microbiota composition of IBS patients after the FMT.