We hypothesize that senescent-dependent changes in airway and lung parenchymal tissue of C57Bl/6J (B6) mice are not synchronized with respect to altered lung mechanics. Furthermore, aging modifications in elastic fiber and collagen content of the airways and lung parenchyma are remodeling events that differ with time. Quasi-static pressure-volume (PV) curves and impedance measurements of the respiratory system were performed in 2-, 20- and 26-month old B6 mice. From the PV curves, lung volume at 30 cmH₂O pressure (V₃₀) and respiratory system compliance (Crs) were significantly (P < 0.01) increased between 2 and 20 months, representing 80-84% of the increase occurring between 2 and 26 months of age. Age-dependent changes in tissue damping (G) and tissue elastance (H) were analogous to changes in V₃₀ and Crs. In contrast, significant (P < 0.05) decreases in airway resistance (R) occurred between 20 and 26 months of age, representing a 71% (P > 0.05) change of total decrease occurring through 26 months. Morphometric analysis of the elastic fiber content in lung parenchyma was significantly (P < 0.01) decreased between 2 and 20 months of age. To the contrary, collagen content was increased significantly (P < 0.01) only at 26 months of age. In conclusion, age-dependent changes in airway and lung tissue mechanics are not synchronized in B6 mice. Moreover, the reduction in elastic fiber content with age is an early lung remodeling event, and the increased collagen content in the lung parenchyma occurs later in senescence.