The aim of this study was to analyze the morphological aspects of the liver parenchyma components in three stages of age in Holtzman rats. The livers of 33 female rats (Rattus norvegicus albinus, Holtzman) aged 120 days (G1 -young), 180 days (G2 -adults) and 540 days (G3 -elderly), with natural aging were studied. The material was processed and submitted to picrosirius technique and polarized light for visualization of collagen fibers, Periodic Acid -Schiff Reactive (PAS) to evidence the glycogen and stained nuclei to search for glycogen and mucus substances. After obtaining the percentage of birefringent collagen, a two-way analysis of variance (TwoWay ANOVA) was performed followed by Tukey's post-test (p<0.05) and for collagen, the analysis of variance was the One-way ANOVA. Morphological analysis of the liver showed normal features of the lobular parenchyma of the liver (hepatocytes, sinusoid capillaries, collagen fibers and blood vessels), but with mild inflammatory infiltrate in the portal space in some animals. Morphometric analysis did not reveal differences between groups regarding the frequency of nuclei and sinusoid capillaries, although this occurred in the "others" parameter between G1 and G2. Glycogen was present in all three groups. G1 presented the smallest amounts of birefringent collagen fibers, followed by G2; G3 showed significantly higher values of birefringent collagen fibers. The results obtained allowed us to conclude that the most relevant alterations obtained during the process of senescence of the rats' liver referred to the more accentuated presence of collagen fibers.