In 13,700 patients who received one or more lumbar disc injections of chymopapain, 401 complications, adverse reactions, and delayed untoward events were recorded, including eight deaths. The deaths were secondary to anaphylaxis, pulmonary embolism, discitis with subacute bacterial endocarditis, ruptured abdominal aortic aneurysms (two patients), encephalitis (of unknown etiology), and myocardial infarction. Of these, the deaths secondary to anaphylaxis and discitis with subacute bacterial endocarditis can be attributed directly to the procedure of chemonucleolysis.