Shock lung can be considered a relatively new pathologic syndrome. Its rapidly increasing incidence is a tribute to advanced sophistication in the salvage of severely traumatized patients and in those undergoing major surgery who would not have survived 25 years ago. No single factor can be credited as the sole precipitator of this syndrome. Alone, many of the factors may be insignificant; but combined they are often synergistic and end in a respiratory death. Although all of the mechanisms and interrelationships are not known for every case, early recognition of the specific contributing etiologies aid in both the prevention and, when that fails, in the treatment of shock lung. Today, by careful precise diagnostic monitoring, many cases of post-traumatic pulmonary insufficiency, i.e., shock lung, can be treated with resultant cure. The term shock lung is valuable only in alerting the physician to the fact that the patient is in "big trouble." The physician must then try to sort out all of the possible factors and treat each accordingly. We might compare the end result of shock lung to the end stage of renal disease. The fact is that they are both nonspecific responses of an end organ to many different and interrelated etiologies. To expect to define a single, all encompassing etiology is pure fancy.