Objective <p>The existing evidence regarding the impact of tamoxifen on lipoprotein(a) and apolipoproteins remains inconsistent. Therefore, this updated meta-analysis of randomized controlled trials (RCTs) aims to enhance the quality of evidence concerning the effects of tamoxifen on these lipid parameters.</p> Methods <p>Eligible RCTs published up to October 2024 were meticulously selected through a comprehensive search. A meta-analysis was then performed using a random-effects model, and results were presented as the weighted mean difference (WMD) with a 95% confidence interval (CI).</p> Results <p>Findings from the random-effects model revealed an increase in ApoA-I (WMD: 15.22 mg/dL, 95% CI: 6.43–24.01, P = 0.001), alongside decreases in ApoB (WMD: −9.33 mg/dL, 95% CI: −15.46 to −3.19, P = 0.003) and lipoprotein(a) (WMD: −3.35 mg/dL, 95% CI: −5.78 to −0.91, P = 0.007) levels following tamoxifen treatment in women. Subgroup analyses indicated a more significant reduction in lipoprotein(a) levels in RCTs with a duration of ≤24 weeks (WMD: −3.65 mg/dL) and in studies using tamoxifen doses of ≥20 mg/day (WMD: −4.53 mg/dL).</p> Conclusion <p>This meta-analysis provides evidence that tamoxifen leads to a decrease in lipoprotein(a) levels, along with reductions in ApoB and increases in ApoA-I among women.</p>