ObjectiveTo assess the cosmetic outcomes and adverse events of MammoSite balloon brachytherapy for Accelerated Partial Breast Irradiation following breast-conserving surgery for patients with early stage breast cancer. MethodsWe searched PubMed, EMbase, Chinese Biomedical Database, Chinese Studies Online, China Journal Full-text Database up to March 2016, to collect clinical trials about MammoSite balloon brachytherapy following breast-conserving surgery for early stage breast cancer. And meta-analyses were performed by OpenMeta and Stata softwares. ResultsTwenty trials involving 3 796 patients were enrolled. The single arm meta-analysis results showed that:the cosmetic results were rated as excellent to good in 93% (95%CI 0.91 to 0.96), and the 5-year incidence of ipsilateral breast tumor recurrence (IBTR) was 3% (95%CI 0.020 to 0.040). ConclusionTo carry out the conclusion above, we still need controlled trials, especially randomized controlled trials (RCTs) to prompt further verification.