AbstractCoronavirus disease 2019 (COVID-19) has quickly turned into a health, financial and societal problem globally. The complex pathogenesis of severe acute respiratory syndrome coronavirus centers on the unpredictable clinical progression of the disease, which may evolve abruptly and results in critical and life-threatening clinical complications. Effective laboratory biomarkers that can classify patients according to risk of progression to severe disease are essential for ensuring timely treatment. Gal-3BP is a human secreted protein with innate immune functions, which is upregulated in viral infections, promotes inflammation and has been shown to induce IL-6 expression. In this study, Gal-3BP plasma levels were measured retrospectively in a cohort of 84 hospitalized COVID-19 patients. These were classified as having either “non-severe” or “severe” disease. Compared to healthy controls, Gal-3BP plasma levels were markedly increased in COVID-19 patients (P < 0.0001). Moreover, the levels were higher in severe than in non-severe patients (P < 0.05). As expected, patients with severe disease had plasma levels of IL-6 higher than patients with non-severe disease (P < 0.01). In non-severe disease patients, Gal-3BP levels collected at a late stage (13.3 + 5.7 days after the first positive PCR result) were significantly lower than those collected at an early stage (4.2 + 2.9 days form the first positive PCR result). Larger prospective analyses are needed to strength our understanding of the prognostic utility of Gal-3BP in COVID-19 patients.