Aim. To study the parameters of 24-hour blood pressure monitoring in patients with polycythemia vera and to determine their informational value for the diagnosis of heart damage.Materials and methods. Blood pressure parameters were monitored daily in 63 patients with I–IIB stage polycythemia vera and 52 healthy individuals to determine the occurrence of their pathological types. The sensitivity and specificity of the studied parameters were evaluated using ROC analysis for early diagnosis of heart damage in polycythemia patients. The obtained information was processed in Statistica 25.0.Results. An analysis of blood pressure load showed that 47.6%, 30.1% and 34.9% of polycythemia patients suffer from systolic arterial hypertension (p = 0.012), daytime diastolic arterial hypertension (p = 0.03), and nocturnal diastolic arterial hypertension (p = 0.001), respectively. In comparison with healthy individuals, polycythemia patients experienced a higher variability of systolic (p<0.002) and diastolic (p<0.001) blood pressure, as well as the morning surge of systolic pressure (p = 0.014), more frequently. In 69.8% of polycythemia patients, pathological types of 24-hour blood pressure profile – with either insufficient or excessive nocturnal reduction – were observed. Informative parameters of heart damage in polycythemia patients were found to include blood pressure load, minimum daytime systolic and diastolic blood pressure, and the rate of nocturnal decrease in diastolic pressure.Conclusions. (1) Systolic-diastolic arterial hypertension was detected in half of polycythemia patients, with pathological types of 24-hour blood pressure profile observed in the majority of patients. (2) The parameters of 24-hour blood pressure monitoring can be used for early diagnosis of heart damage in patients with polycythemia vera.