Introduction. Pulmonary hypertension (PHT) is a quite frequent echocardiographic finding in hyperthyroid patients and it regresses slowly under therapy with thiamazol. Aim. The aim of the study was to follow the evolution of PHT over a period of a year, in two groups of hyperthyroid patients. Material and Methods. We followed up two groups of patients: one consisted of patients with chronic Graves Basedow disease, some of them with good response to antithyroidian treatment and some other patients with repeated episodes of decompensation despite medical therapy.The second group contained new diagnosed cases, a supgroup of patients with overt hyperthyroidism and one with subclinical forms. All 4 subgroups were followed over a period of 12 months. These subjects underwent thyroid hormone determinations and echocardiographic examination at 0, 1, 3, 6 and 12 months. Results. Our study group consisted of 92 patients with hyperthyroidism of different etiologies. None of the subjects had pulmonary or cardiovascular diseases severe enough to cause PHT by itself. We determined the presence and severity of pulmonary hypertension at the initial visit and followed its evolution at each scheduled visit in all four subgroups. All patients got antithyroidian therapy with thiamazol, but some chronic cases, with episodes of exacerbation, needed adjustments of their initial treatment. We noticed that PHT appeared in a higher percent and was more severe in the patients with severe hyperthyroidism or in the chronic cases with poor therapeutic response. We observed after some months a tendency to regression in the well controlled patients or in those with subclinical disease. Conclusion. The duration and severity of hyperthyroidism had a strong influence on the evolution of pulmonary hypertension in our patients. [ABSTRACT FROM AUTHOR]