Clinicians are required to assess abnormal liver chemistries on a daily basis. The most common liver tests done are serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and bilirubin. This slide set discusses the new clinical guideline from the American College of Gastroenterology on the first recommendations in over a decade for the evaluation of abnormal liver chemistries. For the first time in a liver test guideline, the authors define a normal healthy serum ALT level based on gender and recommend that levels above this should be assessed.