Pulmonary hypertension (PH) is frequent complication in patients of advanced heart failure and it is a sign of poor clinical outcome (Ghio et al, 2001). We studied rats recovering in air for two weeks after hypoxic PH induced in isobaric hypoxic chamber (FiO2 = 0.1, 3 wks). To accelerate the recovery we used antioxidant N-acetylcysteine (NAC) (group H+NAC, n = 9, 20 g / l drinking water, 2 wks), Rho-kinase inhibitor fasudil (group H+F, n = 10, 30mg/kg/day, i. p., 2 wks). Control group recovered in ambient air was treated with saline (n = 9). The third experimental group recovered in hyperoxic environment (FiO2 = 0.3, 2 wks) (group H+HO, n = 7), controls (n=8) recovered in air. After two weeks of recovery all rats were anesthetized with Thiopental (40 mg/kg, i.p.) and pulmonary arterial mean blood pressure, cardiac output and ratio of the weights of the right and left heart ventricles were determined. Groups H+NAC, H+HO and relevant controls did not differ in any of measured parameters. In rats treated with fasudil the mean pulmonary arterial blood pressure was after two weeks recovery significantly lower (20 ± 4 mmHg, mean ± SEM) than in controls (27 ± 4 mmHg). The ratio of the weights of the right and left heart ventricles, however, did not differ from controls. Cardiac output did not differ between the groups. Inhibition of Rho kinase pathway but not change in metabolism of oxygen radicals are related to the pattern of recovery of lung circulation after chronic hypoxia.