The authors performed the study of the influence of spa treatment in Wysowa Health Resort on heart function in 294 subjects during their 24-day stay in sanatorium within three groups of patients: 28 with diabetes mellitus, 63 with arterial hypertension and a control group. Hemodynamic parameters were recorded by non-invasive impedance cardiography twice: in the first three days of spa treatment and again in the last three days of a 24-day stay. The following hemodynamic parameters were evaluated: SBP, DBP, MAP, CI, SVRI, IC, ACI, LCWI, EF, SI, EDI, TFC, HR. Relation of hemodynamic parameter changes on other measurable features was described in each group by correlation analysis. A small value of Pearson r coefficient proves a small relation among the examined variables. Both in the control group and in diabetic patients and also in patients with arterial hypertension, a spa treatment in Wysowa Health Resort does not show a significant influence to the examined hemodynamic parameters measured by impedance cardiography.