Background: Gastrointestinal stromal tumors (GISTs) are characterized by the expression of c-KIT (antigen CD 117) and are the most common mesenchymal tumors of the digestive tract. An important complication, although infrequently described in the literature, is the rupture of these tumors with accompanying hemoperitoneum. Methods: We performed a retrospective evaluation of the clinical history and radiologic records of 23 patients with a diagnosis of GIST and anatomopathologic and immunohistochemical confirmation at our hospital between 1999 and 2004. Results: In five cases there was rupture of the primary tumor (four gastric and one jejunal). In all five cases ultrasonographic and computed tomographic examinations showed a heterogenic tumor of laminated or whirled appearance, associated with echogenic or dense ascites. No relation was found between histologic criteria of malignancy and the rupture. Four patients underwent surgical intervention, three of them urgently. Two of five patients died. There was a sixth case with rupture of a hepatic metastasis, with accompanying hemoperitoneum and subcapsular hematoma. This patient died at 3 months, after recurrence of bleeding. Conclusions: The finding of a heterogeneous tumor of laminated or whirled appearance associated with ascites with characteristics compatible with hemoperitoneum in an appropriate context must lead to a suspicion of the existence of a ruptured GIST. Background: Gastrointestinal stromal tumors (GISTs) are characterized by the expression of c-KIT (antigen CD 117) and are the most common mesenchymal tumors of the digestive tract. An important complication, although infrequently described in the literature, is the rupture of these tumors with accompanying hemoperitoneum. Methods: We performed a retrospective evaluation of the clinical history and radiologic records of 23 patients with a diagnosis of GIST and anatomopathologic and immunohistochemical confirmation at our hospital between 1999 and 2004. Results: In five cases there rupture of the Primary tumor (four gastric and one jejunal). In all five cases ultrasonographic and computed tomographic examinations showed a heterogenic tumor of laminated or whirled appearance, associated with echogenic or dense ascites. No relation was found between histologic criteria of malignancy and the rupture. Four patients underwent surgical intervention, three of them urgently. Two of five pati There was a sixth case with rupture of a hepatic metastasis, with accompanying hemoperitoneum and subcapsular hematoma. This patient died at 3 months, after recurrence of bleeding. Conclusions: The finding of a heterogeneous tumor of laminated or whirled appearance associated with ascites with characteristics compatible with hemoperitoneum in an appropriate context must lead to a suspicion of the existence of a ruptured GIST.