The depth of our knowledge regarding mast cells has widened exponentially in the last 20 years. Once thought to be only important for allergy-mediated events, mast cells are now recognized to be important regulators of a number of pathological diseases. The revelation that mast cells can influence organs, tissues, and cells has increased interest in mast cell research during liver disease. The purpose of this review is to refresh the reader on the development, type, and location of mast cells and to review recent work that demonstrates the role of hepatic mast cells during diseased states. This review will focus primarily on liver diseases and mast cells during autoimmune disease, hepatitis, fatty liver disease, liver cancer and aging in the liver. Overall, these studies demonstrate the potential role that mast cells have in disease progression.