OBJECTIVES: The treatment of irritable bowel syndrome (IBS) is a challenge because its cause remains unknown. Previous clinical trials to examine the efficacy of probiotic Bifidobacterium infantis 35624 in patients with IBS showed inconsistent findings. This study aimed to assess the combined effect of B. infantis on reducing symptom severity of IBS based on the published data.  METHODS: A meta-analysis was conducted using fixed-effect models to estimate the combined effect of B. infantis on primary outcomes, which included abdominal pain, bloating/distention, and bowel habit satisfaction. A systemic review was performed based on PubMed, Cochrane Library, and EMBASE databases to identify the randomized controlled trials comparing probiotics B. infantis with placebo in treating IBS symptoms, published up until December 31, 2015. Standardized mean differences (SMD) method was used to combine data since scales to measure the efficacy of probiotics were different among studies. RESULTS: A total of 5 studies were identified as suitable for inclusion, including 3 studies for B. infantis only and 2 studies for composite probiotic which contained B. infantis