Aims Electrocautery (EC) remains the dominant dissection tool in modified radical mastectomy (MRM) for breast cancer. However, ultrasonic dissection devices (UDD) have emerged as popular alternatives on the basis that their mechanism of action limits tissue damage resulting in decreased blood loss, seroma formation and post-operative drainage. A systematic review and meta-analysis was performed to compare surgical outcomes for EC versus UDD in MRM surgery. Methods MEDLINE, EMBASE, PubMed and the Cochrane Database were searched and a comprehensive systematic review and meta-analysis performed according to PRISMA guidelines, comparing EC versus UDD in MRM for breast cancer. Outcomes of interest were post-operative drainage, incidence of seroma, intra-operative blood loss and operative time. Meta-analysis was performed using a random effects model to aggregate the data. Odds ratios (OR) were used as the summary statistic for dichotomous data and mean difference (MD) for continuous data. Data heterogeneity was assessed using the I2 statistic. Results Nineteen eligible peer-reviewed studies were analysed involving 1501 patients, UDD:744 EC:757. We demonstrated that in MRM, UDD significantly reduced post-operative drainage (MD = 312.26, 95% confidence interval (CI): 102.59-521.93, p = 0.004); seroma (OR = 0.51, 95% CI: 0.39-0.68, p Conclusion Using UDD in MRM for breast cancer presents significant advantages in decreasing post-operative drainage, seroma and intra-operative blood loss, without lengthening operating time compared to EC. It therefore appears favourable, however further cost-effectiveness analysis would be beneficial to guide selection.