A gastrointestinal stromal tumor (GIST) is a rare tumor of the gastrointestinal tract. Although stomach is the most frequent site of occurrence, GISTs can arise from anywhere in the gastrointestinal tract. The most common symptoms are vague and nonspecific abdominal pain or discomfort. We would like to present a GIST case with the complaint of acute abdominal pain and fever due to an accompanying complex adnexial mass. A 47-year-old female patient with sudden onset abdominal pain and fever applied at our clinic. A 8 cm diameter sized, complex, solid mass on the ultrasonografic examination was found. Her temperature was 38.6 degrees C and on her laboratory examination, leukocyte and CRP values were 27.400 and 254, respectively After an initial diagnosis of tuboovarian abscess, the patient was internalized. Abdominal CT revealed a solid lesion originating from small bowel resulting in signs of sepsis due to a closed perforation. Resection of the mass was performed and the postop pathology report was GIST. Patient had adjuvant imatinib therapy Although GIST's are mostly seen in stomach with vague symptoms, large sized GIST's which occur in the lower abdomen can be complicated and present as having a tuboovarian abscess clinic.