Effects of chronic high-altitude hypoxia on the remodeling of right ventricle were examined in three age groups of rats: 2, 6 and 18 months (mo). The extent of right ventricular hypertrophy (RVH) showed an age-associated diminution. Right ventricular cell (RVC) size and pericellular fibrosis showed a significant increase in the 2-mo- and 6-mo-old exposed rats but not in the 18-mo-old exposed rats compared to control. An hyperplasic response was underscored in the three exposed age groups but appeared less pronounced in the 18-mo-old rats. A significant decrease in the transient outward potassium current (I_to) density was observed in RVC only in the 2-mo-old exposed group compared to the control. In the control group there was a clear tendency for I_to density to decrease as a function of age. The sustained outward current (I_sus) density was modified neither by the hypoxia condition nor by the age. Neither the cytochrome c oxydase (Cox) activity nor the heat shock protein 72 (HSP72) content in right ventricle (RV) were altered after hypoxic exposure regardless of the age. The noradrenaline content in RV was significantly decreased in each age group exposed to hypoxia when compared with their age-matched control group. Our findings indicate that the remodeling (at morphological and electrophysiological levels) induced by chronic hypoxia in the RV can be decreased by the natural ageing process.