The aim of our study was to evaluate the lipoprotein changes that occur during acute coronary events, and to determine the lipoprotein threshold levels that identify patients who require future statin therapy. Lipoprotein levels were measured at admission, at 6 hours, the morning after admission, before discharge, and 3 months after discharge in patients with myocardial infarction and unstable angina. Patients with myocardial infarction on thrombolytic therapy (n = 63) and patients with unstable angina (n = 33) had a decrease in low-density lipoprotein (LDL) cholesterol levels ≤24 hours after admission (−12 ± 20% and −6 ± 23%, respectively), but these levels returned to baseline before discharge. In patients with myocardial infarction who did not receive thrombolytic therapy (n = 37), the decrease was more gradual and peaked before hospital discharge (−7 ± 19%). There was good correlation between LDL cholesterol levels at admission and after discharge, especially in normotriglyceridemic patients. Over 90% of patients with LDL cholesterol ≥125 mg/dl on the morning after admission were candidates for statin therapy after discharge. Thus, the need for future statin therapy can be predicted with fair reliability during the initial 24 hours after admission. However, elevated baseline triglyceride levels significantly affect these LDL cholesterol changes and complicate prediction of long-term lipoprotein levels.