The tight-skin (Tsk) and beige (bg) mutants of the C57B1/6J strain of mouse spontaneously develop air-space enlargement reminiscent of human emphysema. To determine if this enlargement is accompanied by matrix destruction, as in the human disease, we examined the elastin and collagen matrices of the lungs of both mutants. The ultrastructure of these matrix components was separately visualized by scanning electron microscopy following controlled alkali digestion, which preserves collagen, and formic acid digestion, which enables visualization of elastin. Significant elastin destruction suggestive of an elastolytic process was observed in the lungs of Tsk mice. Thickening of elastin lamellae was observed in the lungs of bg mice, suggesting that congenital matrix remodeling may underlie air-space enlargement in this strain.