Ibudilast (3-isobutyryl-2-isopropylpyrazolo-[1.5a] pyridine) is a prostacyclin mediated vasodilator and anti-platelet agent that has a relatively long duration of action and is orally active. Non-insulin dependent diabetic patients were studied to evaluate the effects of ibudilast on hemodynamic changes in the circulation by two dimensional Doppler echography and laser blood flowmetry. Before and 1 h after administration of ibudilast (10 mg) or elastase (1800 U), the cross-sectional area (Area) of the dorsal pedis artery and its Blood Flow Index (BFI), calculated from maximum flow velocity and Area, were determined. Dermal microcirculatory blood volume (MCBV) was also measured with the laser blood flowmeter. In the ibudilast group, the Area was significantly increased from 2.72±0.32 to 3.21±0.35mm2 (Mean±SE, p<0.05). The BFI was also siginificantly increased from 28.3±3.7 to 37.0±5.2 (p<0.01). In the ibudilast group, MCBV was also significantly increased from 3.82±0.70 to 4.96±0.71 ml/min/100g tissue (p<0.01). No significant changes were observed in the data of the elastase group, and no side effects were observed in any of the patients in either of group. The results of this study suggest that ibudilast may be useful in ameliorating diabetic macro-and microangiopathy of the lower limbs.