Abstract: The present invention provides for the use of a calpain inhibitor for the treatment of allergy diseases, inflammatory diseases and autoimmune diseases. In particular, it has been found that inhibition of calpain within mast cells decreases the release of chemical mediators into the surrounding environment, resulting in a decreased local inflammatory response. The present invention also provides for a method of decreasing IgE-dependent mast cell degranulation, mast cell mediator release and cytokine production in mast cells, comprising the step of administering to the mast cells an effective amount of a calpain inhibitor.