Aims & Objectives: A lactate-albumin ratio (LAR) greater than 0.5 measured early in the course of critical illness in children is associated with mortality and development of MODS. It is currently uncertain if alterations in microcirculation in children with sepsis are related to LAR. Methods: An observational cross-sectional study was conducted between January 2021-January 2024. Albumin, and lactate were assessed during the first six hours of PICU admission. Capillary density 4-6 microns (CD 4-6), capillary blood flow (CBV), glycocalyx degradation (perfused boundary region - PBR: normal less 2.0 microns), and microvascular health score (MVHS™ - CBV/PBR ratio) were measured using sublingual videomicroscopy. The primary outcome was the association between LAR and changes in microcirculation. Results: A total of 192 children (median age of 5.2 years [IQR 0.52-11.11]) were included. Patients with elevated LAR had lower CD 4-6 microns (21.2 [IQR 12.4-31.1] 10-2 mm/mm2 vs 28.4 [IQR 17.1-52.1] 10-2 mm/mm2; p<0.01) and less capillary blood flow (65.6 [IQR 34.5-81.4] 103μm3 vs 77 [IQR 49.6-87.9] 103μm3; p=0.04) with no differences in PBR (p=0.95). These patients had a higher odds of prolonged capillary refill time (OR 1.57 CI 95% 1.03-2.40; p=0.03) and higher doses of vasoactive (VIS 18 [IQR 12-33] vs 6.5 [IQR 4.5-20.1]; p<0.01). A normal LAR is associated to a decreased risk of microcirculatory damage evaluated by the MVHS™ (aOR 0.77 CI 95% 0.65-0.93; p<0.01). Conclusions: In children with sepsis, an elevation of LAR is associated with an alteration in microcirculation (microvascular density and flow). LAR is a potential useful biomarker of microcirculation damage in sepsis. Keywords: biomarkers, septic shock, perfusion, Mortality, microcirculation