Background--Findings from recent studies show that microvascular injury consists of microvascular destruction and intramyocardial hemorrhage (IMH). Patients with ST-segment elevation myocardial infarction (STEMI) with IMH show poorer prognoses than patients without IMH. Knowledge on predictors for the occurrence of IMH after STEMI is lacking. The current study aimed to investigate the prevalence and extent of IMH in patients with STEMI and its relation with periprocedural and clinical variables. Methods and Results--A multicenter observational cohort study was performed in patients with successfully reperfused STEMI with cardiovascular magnetic resonance examination 5.5 ±1.8 days after percutaneous coronary intervention. Microvascular injury was visualized using late gadolinium enhancement and T2-weighted cardiovascular magnetic resonance imaging for microvascular obstruction and IMH, respectively. The median was used as the cutoffvalue to divide the study population with presence of IMH into mild or extensive IMH. Clinical and periprocedural parameters were studied in relation to occurrence of IMH and extensive IMH, respectively. Of the 410 patients, 54% had IMH. The presence of IMH was independently associated with anterior infarction (odds ratio, 2.96; 95% CI, 1.73-5.06 [P < 0.001]) and periprocedural glycoprotein IIb/IIIa inhibitor treatment (odds ratio, 2.67; 95% CI, 1.49-4.80 [P < 0.001]). Extensive IMH was independently associated with anterior infarction (odds ratio, 3.76; 95% CI, 1.91-7.43 [P < 0.001]). Presence and extent of IMH was associated with larger infarct size, greater extent of microvascular obstruction, larger left ventricular dimensions, and lower left ventricular ejection fraction (all P < 0.001). Conclusions--Occurrence of IMH was associated with anterior infarction and glycoprotein IIb/IIIa inhibitor treatment. Extensive IMH was associated with anterior infarction. IMH was associated with more severe infarction and worse short-term left ventricular function in patients with STEMI.