['VSL#3 is a probiotic mix preparation reported to be effective in the treatment of mild to moderately active ulcerative colitis. We aimed to perform a systematic review of the literature and a meta-analysis of studies on its efficacy.', 'The searched databases included PubMed, Scopus, and ScienceDirect. The Mantel-Haenszel method was used to pool the effect- ize across studies, and the odds ratios (ORs) and 95% confidence intervals (CIs) of experiencing a specific outcome were calculated.', 'Five studies with 441 patients were identified. The pooled remission rate was 49.4% (95% CI, 42.7-56.1). Only 3 low risk of bias studies with 319 patients met the inclusion criteria for further analysis. A total of 162 patients received 3.6 × 10 CFU/d VSL#3, and 157 patients received placebo. A total of 95% of patients received concomitant therapies with 5-ASA and/or immunomodulators. The Ulcerative Colitis Disease Activity Index was used to define response and remission. A >50% decrease in the Ulcerative Colitis Disease Activity Index was achieved in 44.6% of the VSL#3-treated patients versus 25.1% of the patients given placebo (P = 0008; OR, 2.793; 95% CI, 1.375-5.676; number needed to treat = 4-5). The response rate was 53.4% in VSL#3-treated patients versus 29.3% in patients given placebo (P < 0001; OR, 3.03; 95% CI, 1.89-4.83; number needed to treat = 3-4). The remission rate was 43.8% in VSL#3-treated patients versus 24.8% in patients given placebo (P = 0007; OR, 2.4; 95% CI, 1.48-3.88; number needed to treat = 4-5). No serious side effects were reported.'] Is probiotic mix VSL # 3 effective adjunctive therapy for mild to moderately active ulcerative colitis : a meta-analysis?