The alanine aminotransferase test, also known as ALT, is one of a group of tests known as liver function tests (or LFTs) and is used to monitor damage to the liver. The alanine aminotransferase test (ALT) can reveal liver damage. It is probably the most specific test for liver damage. However, the severity of the liver damage is not necessarily shown by the ALT test, since the amount of dead liver tissue does not correspond to higher ALT levels. Also, patients with normal, or declining, ALT levels may experience serious liver damage without an increase in ALT. Nevertheless, ALT is widely used, and useful, because ALT levels are elevated in most patients with liver disease. Although ALT levels do not necessarily indicate the severity of the damage to the liver, they may indicate how much of the liver has been damaged. ALT levels, when compared to the levels of a similar enzyme, aspartate aminotransferase (AST), may provide important clues to the nature of the liver disease. It is a part of Liver Function Test. It is always advisable to go for complete profile, as level of each test in profile are considered while making decision on diagnosis as well as monitoring the treatment.