ObjectiveTo evaluate the effect of intravenous immunoglobulin (IVIG) on prognosis of patients with idiopathic systemic capillary leakage syndrome (ISCLS). MethodsCase reports and case series related to IVIG on prognosis of ISCLS were electronically searched from the PubMed, CNKI and WanFang Data databases from inception to December 31, 2021. Two researchers screened literature and extracted the data independently, then, prognostic data were analyzed. ResultsA total of 143 case reports (175 patients) and 5 case series (169 patients) were included. About 75% of patients had monoclonal gamma globulin, most of those were IgG κ type. A total of 40 patients received prophylaxis with IVIG, most of whom received a high dose (2 g/kg) of IVIG per month. The 5-year and 10-year survival rates of ISCLS patients receiving IVIG secondary prevention treatment were 96% and 72%, respectively, significantly better than the rates of 66% and 43% in the group without IVIG. The median number of acute episodes per year was 0 (0-20) in the group receiving secondary prevention with IVIG and 2 (1-16) in the group not receiving IVIG. ConclusionHigh-dose (2g/kg) IVIG can improve the long-term survival of ISCLS patients, but efficacy of IVIG in acute episodes is unclear.