The purpose of the study was to compare the in vivo effects of two low-osmolar radiographic contrast media, a monoionic (sodium/-meglumine ioxaglate, Hexabrix) and a non-ionic one (iopromide, Ultravist 300) on the cutaneous microcirculation in patients with peripheral arterial occlusive disease in a prospective randomised double-blind study. In 20 patients with peripheral arterial occlusive disease scheduled for percutaneous transluminal angioplasty skin microcirculation was assessed by laser Doppler fluxmetry and transcutaneous oxygen tension measurements at the foot dorsum for continuous recordings of the cutaneous microvascular perfusion and skin oxygenation. Before angioplasty 10 ml nondiluted contrast medium was injected intraarterially and the acute effect on transcutaneous oxygen tension and laser Doppler flux was registered. Mean laser Doppler flux and oxygen tension were evaluated initially, after arterial puncture and after contrast medium injection. In addition, flux motion was analysed with respect to frequency and amplitudes changes. No significant changes in laser Doppler flux and fluxmotion patterns were found between both groups after contrast medium injection. However, mean transcutaneous oxygen tension of the patients receiving monoionic ioxaglate dropped significantly (P = 0.01). The differences of both contrast media on red blood cell aggregation shown in vitro do not correlate to intravital microcirculatory measurements in patients with arterial occlusive disease of the lower limb. Microvascular skin blood flow and flux motion at the foot in these patients do not change significantly after intraarterial injection of ioxaglate and iopromide. However, oxygen supply of the skin is transient impaired after interarterial injection of the anionic contrast agent ioxaglate, which was not associated with clinical symptoms.