Taking into account the principal objectives of the treatment of acute cerebrovascular insufficiency of the nonhemorrhagic type (stabilization of cardiovascular function, reduction of cerebral edema and improvement of the flow properties of blood and of the microcirculation), several therapeutic regimens were studied to establish the value of the hemorheologic agent pentoxifylline (Trental®) in this clinical condition. Firstly, a 2-week double-blind study was carried out to compare twice daily intravenous infusion of 200 mg pentoxifylline with that of a combination of hexobendine, ethamivan and etofylline in patients with nonhemorrhagic stroke. 25 patients were assessed in the pentoxifylline group compared with 32 in the comparator group. A considerable improvement (complete rehabilitation) was achieved in 36% of cases with pentoxifylline compared with 25% receiving the comparator. No improvement or some deterioration of pathological symptoms was detected in 8% of patients treated with pentoxifylline compared with 21% of those receiving the comparator. 2 patients died in the pentoxifylline group compared with 8 in the comparator group. A 2-year retrospective study was then carried out to compare results obtained in stroke patients treated with or without pentoxifylline. One third of the patients treated with pentoxifylline were completely or almost completely rehabilitated compared with only about one fifth of the patients receiving other parenteral treatments. No change or some deterioration was detected in almost twice as many patients from the group without pentoxifylline as in the groups with pentoxifylline. These results indicate that, apart from the improvement of cardiovascular status and reduction of cerebral edema, the pharmacological amelioration of the flow properties of blood is a promising therapeutic principle in many cases of nonhemorrhagic stroke.