Shenmai Injection (SMI), a Chinese herbal injection, is widely used in China for the adjuvant treatment of patients with dilated cardiomyopathy (DCM), yet its clinical efficacy and safety remain controversial.The aim of this study was to systematically evaluate the efficacy and safety of SMI in the treatment of DCM.Randomised controlled trials (RCTs) of SMI in the treatment of DCM were searched for and collected from the PubMed, EMBASE, Cochrane Library, SinoMed, Wan Fang, CNKI, and VIP databases between the dates of establishment of each database and July 1, 2022. The methodological quality of the included studies was assessed, while the risk of bias was based on the Cochrane Collaboration tool. All data were analysed using the R software. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach was applied to rate the quality of the evidence.In total, 16 RCTs, including 1,455 participants, were examined in this study. Evidence showed that the combination of SMI treatment and conventional treatment appears to significantly increase the clinical efficacy rate (OR=3.65, 95%CI (2.52, 5.28), p < 0.01), improve cardiac function (e.g. increase left ventricular ejection fraction (LVEF) (MD=5.31, 95%CI (4.21, 6.40), p < 0.01), decrease left ventricular end-diastolic dimension (LVEDD) (MD=-4.57, 95% CI (-7.10, -2.04); p < 0.01) and left ventricular end-systolic diameter (LVESD) (MD=-2.46, 95% CI (-3.60, -1.33); p < 0.01), decrease brain natriuretic peptide (BNP) (MD=-215.85, 95% CI (-241.61, -190.10); p < 0.01) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) (MD=-504.42, 95% CI (-687.73, -321.10); p < 0.01), and increase 6-min walk distance (6MWD) (MD=114.08, 95% CI (42.32, 185.85); p < 0.01).In addition, no serious adverse effects associated with SMI were observed during the study period, thus suggesting that SMI is safe. However, the quality of evidence for these results was rated as "very low" to "low", mainly due to the poor methodological quality of the included RCTs, the small sample size, the high heterogeneity, and potential publication bias.In the present work, we provide evidence that combined SMI therapy is beneficial and safe for improving cardiac function in patients with DCM. However, due to limitations posed by the low methodological quality of the included trials, more rigorous and high-quality RCTs are needed to provide solid evidence.Copyright © 2022 Elsevier GmbH. All rights reserved.