Pentoxifylline (oxpentifylline) is an orally active haemorheological agent for the treatment of peripheral vascular disease, cerebrovascular disease and a number of other conditions involving a defective regional microcirculation. Pentoxifylline acts primarily by increasing red blood cell deformability, by reducing blood viscosity and by decreasing the potential for platelet aggregation and thrombus formation. Extensive open and placebo-controlled studies have shown that pentoxifylline 600 to 1200 mg/day for at least 6 weeks is associated with subjective and objective improvements in 60 to 100% of patients with peripheral vascular disease. The most commonly assessed clinical parameter, walking distance, is usually improved by about 100%, although much greater improvements have also been documented. Other parameters which have been clearly improved include lower limb rest pain, paraesthesia, muscle blood flow, cramps and leg ulcers. Pentoxifylline has produced consistently better results than placebo, and in those studies using comparative drugs, better results than nylidrin, adenosine and naftidrofuryl. In patients with cerebrovascular disorders, open studies with pentoxifylline, usually at a dosage of 600 to 1200 mg/day (300 to 600 mg/day in Japan), have shown marked overall clinical improvements in about 85% of patients. Symptomatic improvements in rehabilitation psychometric tests, neuromotor and speech deficits and other subjective symptoms have accompanied increased cerebral blood flow, particularly to ischaemic areas. Pentoxifylline would appear to be useful in most types of cerebrovascular disease including transient ischaemic attacks, sequelae of cerebral thrombosis and haemorrhage, and chronic ischaemic disorders. In patients with chronic cerebrovascular disease pentoxifylline 600 to 1200 mg/day conferred significant clinical benefit compared with placebo and in isolated studies proved to be superior to drugs such as co-dergocrine mesylate, adenosine and pyrithioxine. Preliminary studies indicate that pentoxifylline may also prove useful in vaso-occlusive crises of sickle cell disease, some hearing disorders, disorders of eye circulation, high altitude sickness and asthenozoospermia. Pentoxifylline is usually well tolerated when administered as the conventional controlled release formulation, gastrointestinal symptoms (about 3%) being the most common complaint, although these and other adverse effects have not occurred to a significantly greater extent than with placebo. Thus, pentoxifylline offers a well-tolerated and effective alternative to the treatment options available for patients with peripheral vascular disease.(ABSTRACT TRUNCATED AT 400 WORDS)