Myoglobin is a small heme-containing protein that belongs to the globin family. It is a cytoplasmic protein that is expressed in cardiac myocytes and oxidative skeletal muscle fibres. Myoglobin reversibly binds oxygen and functions as an oxygen storage protein in muscle. It also facilitates the movement of oxygen within muscles and is reported to buffer the intracellular oxygen concentration during increased muscle activity. In cases of acute myocardial infarction (AMI), myoglobin can be detected in blood 1-2 hours after presentation but can also be elevated after skeletal muscle injury, and therefore is not specific for AMI. Historically, myoglobin has been used as an early marker of AMI in conjunction with the CK-MB isoform of creatinine kinase or cardiac troponin (cTn). However, cardiac markers troponin I (cTnI) and cardiac troponin T (cTnT) are now considered to be more specific for myocardial damage and are used in combination with myoglobin for AMI diagnosis.