Introduction: Alzheimer's disease (AD) is the most common phenotype of dementia. Mild cognitive impairment (MCI) due to AD is believed as a prodromal stage of AD. Intravenous immunoglobulin (IVIG) is a classical immunotherapy and potentially reduces AD-type pathology by anti-Aβ, anti-tau, anti-inflammatory effects, and non-antibody-mediated effects. Areas covered: The authors aimed to determine the efficacy and safety of IVIG for AD and MCI due to AD patients. The electronic databases including PubMed, EMBASE, CINAHL, Cochrane Library, and China National Knowledge Infrastructure were searched until March 2019. The results were pooled via a random-effects model. There were five eligible studies with 772 randomized patients with AD and MCI due to AD, which compared IVIG with placebo. Expert opinion: No significant differences were found in the scores of mini-mental state examination and Alzheimer's disease assessment scale-cognitive subscale and number of patients with adverse events. IVIG is well tolerated in the patients with AD and MCI due to AD, even in long-term therapy for 18 months. Insufficient evidences support IVIG in the treatment of patients with AD and MCI due to AD to improve cognition or disease modification. Well-designed randomized controlled trials with large sample sizes are required in the future.