Early studies reported a prolactin surge during electroconvulsive therapy (ECT). The aim of this study is to review and meta-analyze data on ECT-related prolactin changes. A systematic review and meta-analysis was conducted for trials investigating prolactin changes in ECT-treated patients using standard mean differences (SMD, 95% confidence intervals). Subgroup analyses included comparisons of ECT-related prolactin changes in women vs. men, patients receiving different anesthetics, bilateral vs. unilateral and high-vs. low-dose ECT. In six trials including 109 ECT-treated patients and 74 controls, prolactin changes were larger in ECT-treated patients than in controls (SMD = 0.89, 95%CI = 0.55, 1.23, p < 0.001 and 1.03, 95%CI = 0.31, 1.75, p = 0.005 for the fixed and random-effect model respectively), despite heterogeneity in the samples (I2 = 72%, τ2 = 0.62). Effects were led by differences in patients premedicated with methohexital (SMD = 1.14, 95%CI = 0.7, 1.57, p < 0.001 for both fixed and random-effect model). A meta-regression reported significant age effects (coefficient estimate 2.32, 95%CI = −0.73, 3.91, p < 0.01). Additionally, prolactin changes were larger in ECT-treated women than men (SMD = 0.88, 95%CI = 0.58, 1.18, p < 0.001 and 0.99, 95%CI = 0.22, 1.75, p = 0.012 for the fixed and random effect model). Bilateral ECT-treated patients had larger increase than unilateral ECT-treated patients (SMD = −0.81, 95%CI = −1.35, −0.27, p = 0.003 and −0.86, 95%CI = −1.46, −0.25, p = 0.006 for the fixed and random-effect model). Comparisons between high- and low-dose ECT-treated patients could not be conducted. The quality of the studies was overall poor, with four exceptions. Patients receiving ECT had larger prolactin increases than controls. Increases were larger in methohexital-premedicated patients, women vs. men and patients with bilateral vs. unilateral ECT. •ECT-treated patients showed larger prolactin increase compared to controls.•The prolactin increase was considerably larger in ECT-treated women compared to men.•Prolactin increase was larger in bilateral vs. unilateral ECT-treated patients.