Laboratory and feral lineages of mice were subjected to cephalad (+GZ) accelerations, for 1.8 seconds, aboard a solid fuel rocket. Spectrophotometric analysis of bronchoalveolar lavage retrieved post launch revealed significant (p \u3c .001) elevations of protein in the lungs of experimental mice. Sudden transient imposition of a mean +GZ acceleration of 6.22 ± .47 (SD) G, at lift-off, may have induced hypervolemia of basilar pulmonary microvasculature with concomitant migration of fluid and protein from intravascular to juxta-alveolar perivascular compartments. Exudates may have entered bronchiolar airways subsequently gravitating toward alveoli