Background <p>Target weight assessment remains challenging, particularly in children, where ongoing growth adds complexity. Lung ultrasound (LUS) has emerged as a promising tool for assessing hydration, although pediatric data are limited.</p> Methods <p>We conducted a retrospective, single-center study between January and September 2024. Target weight was assessed using clinical examination, pre-dialysis NT-proBNP level, relative overhydration by bioimpedance analysis (BIA), inferior vena cava (IVC) diameter, and LUS score (12-zone protocol). The primary outcome was the association between LUS and other assessment methods. Secondary outcomes included the reliability of LUS with dialysis-related weight loss and its contribution to multimodal evaluation. Mixed-effects regression models were used.</p> Results <p>Sixty-eight dialysis sessions of 10 children on hemodialysis were analyzed. The median pre-dialysis LUS score was 7 (IQR 5–9), which decreased to 4 (IQR 3–6) post-dialysis. LUS correlated significantly with NT-proBNP level (<i>p</i> = 0.006) but not with BIA or IVC. A trend was observed for clinical signs (<i>p</i> = 0.072). Changes in the LUS score correlated with dialysis-related weight loss (<i>p</i> &lt; 0.001).</p> Conclusions <p>LUS is a sensitive, dynamic complementary tool for assessing target weight in pediatric hemodialysis patients. It provides additional information on extravascular fluid status and should be considered within multimodal target weight strategies, especially in cases of discordance.</p> Graphical Abstract <p></p>