The gastrointestinal stromal tumor(GIST)guidelines state that the use of neoadjuvant chemotherapy(NAC)for curable GIST is not apparent. However, NAC is performed for massive rectal GIST at our hospital to reduce surgical invasion and improve surgical results. The cases were a 39-year-old man, a 48-year-old man, and a 78-year-old man. The site was Rb in all cases, and the maximum diameters at the rectal GIST diagnosis were respectively 70 mm, 75 mm, and 60 mm, which were massive tumors. Imatinib mesylate(imatinib)was started as NAC. The duration of NAC was respectively 6, 11, and 12 months. The maximum tumor diameter on preoperative CT was smaller than before NAC, and the average reduction rate was 23%. Two cases underwent laparoscopic abdominal perineal resection, and 1 underwent laparoscopic ultra-low anterior resection and ileostomy. No perioperative complications of Clavien-Dindo classification Grade Ⅱ or higher were unsettled. All patients were in the high risk group and received imatinib as postoperative adjuvant chemotherapy. Currently, respectively 2 years and 3 months, 1 year and 2 months, and 1 year after surgery, all are alive without recurrence. NAC with imatinib has contributed to minimally invasive and radical surgery for giant rectal GIST.