Background <p>Gluteal augmentation with polymethyl methacrylate (PMMA) has gained popularity due to its durability, biostimulatory effects, and minimally invasive nature. However, data on safety and complication rates across different application techniques remain limited.</p> Objective <p>To evaluate complication rates in 5081 PMMA gluteal augmentation procedures performed in 3195 patients over 15 years, comparing three progressively refined techniques.</p> Methods <p>A retrospective cohort study was conducted at two clinical centers in Brazil between 2009 and 2024. Patients were categorized into three groups based on the technique used: Group 1: classic intramuscular injection under local anesthesia; Group 2: ultrasound-guided technique with gluteal mapping; and Group 3: Advanced Gluteal Modeling (MAG) technique with ultrasound guidance and sedation. Complications were assessed through medical record review and included nodules, granulomas, infection, hematoma, and neurological symptoms.</p> Results <p>Among the 3195 patients (97% female), complication rates decreased across the groups: Group 1: 2.1%; Group 2: 1.7%; and Group 3: 1.4%. Nodules were the most common adverse event. No cases of necrosis or long-term neurological deficits were observed. The MAG technique demonstrated the lowest complication rate, attributed to improved precision from imaging and controlled settings.</p> Conclusions <p>The use of PMMA for gluteal augmentation is safe when performed by trained professionals. The MAG technique presented superior safety results, showing that advances in the technique, as well as performance in a controlled environment, can significantly reduce complications.</p> Level of Evidence III <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>