Background <p>Trapezius hypertrophy is a significant aesthetic concern among women. Botulinum toxin has emerged as a potential treatment option for this condition. In this study, we conducted a prospective, randomized, double-blind trial to evaluate the effectiveness and safety of letibotulinumtoxinA specifically for women.</p> Methods <p>We conducted a prospective study between July 2022 and June 2023, recruiting 20 patients seeking treatment for trapezius hypertrophy. LetibotulinumtoxinA (Botulax®) was used as the neurotoxin. The patients were randomized into group A (n = 10, 40 units) and group B (n = 10, 80 units). Each group received different doses of toxin at 10 injection points along the trapezius muscle.</p> Results <p>We analyzed the contour changes in two groups and calculated the average area before and after treatment. After 12 weeks post-treatment, both groups demonstrated a decrease in the trapezius area with statistically significant differences (p = 0.011, p = 0.005). The median satisfactory score was 4, indicating a moderate level of satisfaction in both groups. No statistically significant differences or complications were observed between the groups.</p> Conclusion <p>LetibotulinumtoxinA for trapezius hypertrophy demonstrated efficacy with no differences between two experimental groups. Aesthetic concerns were addressed, enhancing shoulder and neck appearance with a high degree of satisfaction.</p> Level of Evidence I <p>This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors&#xa0;<a href="http://www.springer.com/00266">www.springer.com/00266</a>.</p>