Background <p>Collagen biostimulators, such as poly-L-lactic acid (PLLA) and calcium hydroxyapatite (CaHA), are widely used in facial esthetic treatments to improve skin quality, restore volume, and stimulate neocollagenesis.</p> Objective <p>This study aimed to evaluate the efficacy, durability, and safety of PLLA- and CaHA-based collagen biostimulators in facial esthetic treatments.</p> Methods <p>A systematic literature review was conducted following PRISMA 2020 guidelines. The PICO strategy guided the research question. Searches were performed in April 2024 in the BVS, Medline (via PubMed), and Scopus databases, using standardized descriptors and Boolean operators. Studies published between 2010 and 2024, available in full text in Portuguese, English, or Spanish, were included. Screening was conducted using the Rayyan platform, and the quality of included studies was assessed with the ROB2 tool.</p> Results <p>Fourteen studies met the eligibility criteria. Both PLLA and CaHA demonstrated significant improvements in skin elasticity, wrinkle reduction, and increased facial volume. PLLA maintained its effects for up to 25 months, while CaHA offered results lasting 12 to 18 months. The most frequent adverse effects were mild, including pain and swelling at the injection site. One serious case of compression necrosis was reported with CaHA.</p> Conclusion <p>Both PLLA and CaHA are effective and safe biostimulators for facial rejuvenation. However, further research is needed to standardize techniques and assess long-term safety.</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>