All patients who had intermittent claudication (IC) over an 18-month period were given prescriptions for pentoxifylline (PTFX) 400 mg, three times daily. Patients were required to purchase their medication at a cost of $28 to $35 per month. The drug was administered regardless of the severity of symptoms, and no patient was offered operation without at least a 6-week trial of PTFX. An assessment of the severity of IC was made at the initial visit based on noninvasive data and the impact of the IC on the patient's life-style. One hundred thirty patients were enrolled in the study and were followed for 9 +/- 1 months. Patients were seen every 2 months for treadmill exercise or induced hyperemic testing and interviews until the effects of the medication were determined. The duration of IC before the start of treatment had no effect on the results. IC did not improve in 88 patients (71%) followed for 7.2 +/- 1 month. Thirty-six of these patients stopped the drug themselves because there was no benefit and the expense of PTFX was a hardship. An initial but short-lived improvement in walking was noted in another 13 patients (10%) following 14 +/- 2 months, and the medication was eventually discontinued. Only 23 patients (19%) followed for 11.6 +/- 2 months felt that IC had improved to the point where they did not feel limited in any way. Gastrointestinal symptoms occurred in 13 patients and were severe in eight patients (6%) who stopped taking the medication. The results of PTFX in this group of patients with IC were disappointing at best.(ABSTRACT TRUNCATED AT 250 WORDS)