Threshold pressures for hemorrhage in mouse lung exposed to the fields of an electrohydraulic lithotripter appear to be less than 2 MPa with as few as 10 pulses and with severe damage occurring at levels between 5 and 6 MPa. This is very much smaller than the fields required to fragment kidney and gallstones and smaller than the thresholds for damage to kidney tissues. Fetal lung, in contrast, did not show signs of damage at 20 MPa. The lower sensitivity of fetal lung is consistent with a cavitation-related mechanism for lung damage by shock waves. Since the pressures in these exposures are almost entirely positive, it suggests that the value of negative pressures as predictors of the behavior of gas bodies in tissues should be reconsidered.