The effect of oral pentoxifylline, administered 1,200 mg/day (400 mg slow-release tablets tid) through six weeks, was studied in 10 patients with established deep venous incompetence and persisting venous ulcers. The following parameters were used for verification of the therapeutic result: venous patency (VP) and valvular competence (VC) assessed by means of Doppler ultrasound; venous refilling time (VRT) assessed by photoplethysmography; skin blood flow (SBF) at rest and after tiptoeing exercise, as well as skin perfusion pressure (SPP), both assessed by means of 99mtechnetium clearance technique. Finally, photo documentation of the tissue lesion was obtained, using a two-dimensional (max and min diameter = Dmax, Dmin) metered scale photo. There was an overall good response to the treatment, the studied parameters showing the following changes: VP and VC remained unchanged; VRT improved in 8 patients, SBF increased in 10; SPP slightly improved in 5; and Dmax and Dmin in all 10 patients. Removal or substantial diminution of the ulcers was obtained in 8 patients. These findings indicate that oral administration of pentoxifylline over a period of six weeks supports the conservative treatment and improves considerably the condition of patients with persisting venous ulcers.