Peripheral arterial disease (PAD) is a frequent manifestation of systemic atherosclerosis. In PAD hemorheological parameters were defined as risk factors in a number of studies and several therapeutic agents were tried in these conditions. Our study aims to investigate and compare the in vitro hemorheological effects of various drugs generally used in the parenteral treatment of intermittent claudication and critical limb ischemia. Blood samples of healthy male volunteers were incubated with iloprost, alprostadil, pentoxifylline, sulodexide or pentosan polysulfate at calculated therapeutic serum concentration. Hematocrit (Hct) was determined by microhematocrit centrifuge. Plasma and apparent whole blood viscosities (WBV) were evaluated by capillary viscometer. Red blood cell aggregation was measured by LORCA (laserassisted optical rotational cell analyzer) aggregometer, and LORCA ektacytometer was used for measuring erythrocyte deformability at $37^{circ}C$. Iloprost, alprostadil, and pentoxifylline incubation did not have any significant effect on plasma and apparent WBV. Elongation index increased in samples incubated with alprostadil at low shear stresses 0.95 and 0.53 Pa (p < 0.05). Sulodexide significantly improved WBV and Hct/WBV ratio (p < 0.05). Incubation with pentosan polysulfate resulted in higher WBV, lower Hct/WBV ratio and deterioration in the aggregation parameters (p < 0.05). Sulodexide may have beneficial effect on a macrorheological parameter; alprostadil may improve a microrheological parameter. Hemorheological alterations could be important in PAD patients with hampered vasodilator capacity.