The instant invention provides a method of treating an animal suffering a disease characterized by excessive apoptosis by administering a therapeutically effective amount of at least one serine protease inhibitor and thereafter monitoring a decrease in apoptosis. The inhibitor of the invention includes .alpha..sub.1-antitrypsin or an .alpha..sub.1-antitrypsin-like agent, including, but not limited to oxidation-resistant variants of .alpha..sub.1-antitrypsin, and peptoids with antitrypsin activity. The diseases treatable by the invention include cancer, autoimmune disease, sepsis neurodegenerative disease, myocardial infarction, stroke, ischemia-reperfusion injury, toxin induced liver injury and AIDS. The method of the invention is also suitable for the prevention or amelioration of diseases characterized by excessive apoptosis.