Aim. To evaluate the effect of prior administration of the soluble guanylate cyclase stimulator riociguat on the incidence and severity of reperfusion lung injury after balloon pulmonary angioplasty (BPA) in patients with inoperable form of chronic thromboembolic pulmonary hypertension (CTEPH).Materials and methods. 70 patients with inoperable CTEPH were included in the study. Patients were divided into 2 groups: Group 1 (n=41) – patients who had received PAH-specific therapy with riociguat at the time of BPA, Group 2 (n=29) – patients who underwent BPA without prior administration of riociguat. In the postoperative period all the patients underwent noninvasive artificial ventilation in continuous positive airway pressure mode in order to prevent the development of reperfusion damage of lungs.Results. Patients of group 1 received treatment with riocigiat for 6 months. At the time of BPA patients of both groups were matched for hemodynamic characteristics. In group 1, reperfusion edema above grade 1 occurred in 17.1% of patients, in group 2 – in 20.7% of patients, p=0.702. In group 1, manifestations of grade 3 reperfusion edema were found in 9.8% patients vs. 6.9% patients in group 2, (p=0.638). None of the patients in both groups had grade 4 or 5 reperfusion edema. Values of the index predicting the probability of reperfusion injury (PEPSI) were not significantly different in the group of patients who were pretreated with riociguat and in the group of patients who did not get PAH-specific therapy (p=0,588).Conclusion. There was no reliable evidence that administration of riociguat in recommended doses at least 6 months before BPA results in additional reduction in the incidence and severity of reperfusion pulmonary edema in patients with inoperable CTEPH.