Inclusion criteria:  Patients of age between 18-and 65 years. Have IBS-Symptom Severity Scale (IBS-SSS) score >175. All patients are required to have symptoms for at least 12 months, fulfilling the Rome III criteria with either diarrhoea-predominant irritable bowel syndrome (IBS-D) or mixed constipation and diarrhoea (IBS-M) with bloating or flatulence as predominant symptoms. All patients will undergo appropriate investigations to exclude organic disease.  Exclusion criteria:  History of inflammatory bowel diseases, gastrointestinal malignancy, blood in stool Antibiotic use within 1 month prior to FMT Immunocompromised patient defined as taking immuno-suppressive medications History of opportunistic infections within 1 year prior to FMT, oral thrush, or disseminated lymphadenopathy. Patients who are scheduled for abdominal surgery. Pregnant or lactating women. Patients taking probiotics or taking antibiotics within 4 weeks prior to installation.  Inclusion criteria of donors for FMT:  Close healthy, family members > 18 years old.  Exclusion criteria of donors for FMT:  Pregnancy or lactation History of inflammatory bowel diseases, IBS, chronic abdominal pain, or gastrointestinal malignancy, diarrhea, blood in stool Antibiotic and pre/probiotic use within 1 month prior to FMT. Immunocompromised defined as taking immuno-suppressive medications History of opportunistic infections within 1 year prior to FMT, oral thrush, or disseminated lymphadenopathy.