The authors report a clinical case of malignant gastric and duodenojejunal GIST, in which the only surgical treatment seems to be definitive. In a 69-year-old female, a surgical resection of the gastric and duodenojejunal tumor was performed. Histological analysis showed two spindle cells stromal tumors with mitotic rate >20/10 HPF and its uncommitted origin was demonstrated. Despite the high malignancy degree, the patient refused chemotherapy treatment and there were no local recurrence nor metastasis at a follow-up of 8 years. For this reason and because of the uncertain behavior of histologically benign GIST, the authors propose a lifelong follow-up of all patients managed with potentially curative surgical resection.