Thrombospondin-1, a large matricellular glycoprotein, exerts multifaced biological effects on the cardiovascular system and is correlated with cardiovascular diseases. Its plasma levels and correlation with in-hospital prognosis are yet unclear in the acute coronary syndrome population. The present study aimed to evaluate the correlation between thrombospondin-1 plasma levels and in-hospital adverse events in patients with acute coronary syndrome.This is a cross-sectional study. A total of 341 inpatients with acute coronary syndrome were recruited in Beijing Chaoyang Hosipital from May 2021 to November 2021. The thrombospondin-1 plasma levels were measured, and the in-hospital major adverse cardiovascular events, including all-cause death, recurrent ischemia, arrhythmias, and heart failure, were recorded. This correlation was assessed by logistic regression analysis.The thrombospondin-1 plasma levels were higher in patients with non-ST-elevation myocardial infarction and ST-elevation myocardial infarction compared to those in unstable angina (P < 0.001), while the differences between the two different types of myocardial infarction were not statistically different. Thrombospondin-1 plasma levels were correlated with GRACE score, leukocytes, neutrophils, platelets, troponin I, creatine kinase-MB, D-dimer, C-reactive protein, erythrocyte sedimentation rate, and log10 brain natriuretic peptide. Furthermore, thrombospondin-1 plasma levels were associated with the in-hospital major adverse cardiovascular events in patients with acute coronary syndrome (P = 0.001).Thrombospondin-1 plasma levels were higher in patients with myocardial infarction than those in unstable angina. The high thrombospondin-1 plasma levels were associated with in-hospital major adverse cardiovascular events.Copyright © 2023 Elsevier B.V. All rights reserved.