Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumors in the gastrointestinal tract ― approximately 85% of GISTs have mutations on KIT or PDGFRA gene. But, without mutation of KIT or PDGFRA, GIST could occur associated with neurofibromatosis by the inactivation of NF1 gene. A 27-year-old man presented with hyperpigmented subcutaneous mass on left inguinal fold on birth. Patient has multiple cafe au lait macules on whole body and in family history, parent has Neurofibromatosis type1. Histopathologic examination revealed plexiform neurofibroma. Three of the seven diagnostic criteria were satisfied, and the patient was finally diagnosed with Neurofibromatosis type 1. Abdominal pain occurred one week before the hospital visit. Abdominal-pelvic CT showed diffuse nodular wall thickening on jejunum and needle biopsy was performed. Needle biospy showed c-kit (CD117) positive and spindle cell type GIST. Overall, glevec treatment was started with multiple gist findings on the small bowel wall. Generally, the NF1-associated GIST shows lack of activating KIT mutations, tend to be multiple, and are located predominantly within the small intestine. In this case, due to the morphological characteristics of the GIST, which is different from the conventional one, there was no prominent mass on AP CT. Thus, it is important to know the character of the neurofibromatosis type 1 associated GIST.