BACKGROUND Haemodialysis patients have abnormal blood vessels, and increased morbidity from vascular causes, effects which may potentially be enhanced by erythropoietin (EPO) therapy. METHODS Microcirculatory blood flow was assessed using a laser-Doppler flowmeter in a group of 19 haemodialysis patients before and during treatment with recombinant human (EPO). RESULTS Haemodialysis patients had significantly impaired microcirculatory blood flow under both basal (25 degrees C) and hyperaemic (44 degrees C) conditions by comparison with 19 normal controls (baseline flow, median and range: patients 1.54 (0.28-2.54) volts, controls 3.39 (0.94-5.23) volts, p < 0.001 Mann Whitney U Test; hyperaemic flow, patients 2.69 (1.08-3.82) volts, controls 3.81 (1.32-8.00) volts, p < 0.001). There was no significant influence on microcirculatory blood flow of patient age, duration of haemodialysis, short-term EPO therapy (subcutaneous or intravenous), therapy with a calcium-channel blocker/vasodilator (nifedipine), or radiological evidence of vascular calcification. CONCLUSIONS Haemodialysis patients have an abnormal peripheral microvasculature, which may be relevant to their increased risk of ischaemic tissue damage and poor wound healing.