Gastrointestinal Stromal Tumors (GISTs) are relatively uncommon soft tissue sarcomas that can be located in any part of the digestive system. GISTs originate in specialized nerve cells located in the walls of the digestive system. This case report is about a 53-year-old airman who was recently diagnosed as peritoneal GISTs. He got a surgical removal of the tumor and chemotherapy, including imatinib (Gleevec^®). Although his GISTs have shown excellent clinical progress, he still needs ongoing treatment. This case involves an airline pilot applicant for Class-I medical certification who has had GISTs under chemotherapy.