We report 3 cases of patients with gastrointestinal cancer who were treated with a regimen including oxaliplatin(OX). The patients were presented with fever over 38.0℃, probably due to OX. Case 1: A 73-year-old male. In the second course of bevacizumab(BEV)plus mFOLFOX6 therapy for rectal cancer and liver metastases, chills appeared 1 h and 45 min after the start of OX, and a fever of 38.0℃ appeared 2 h and 35 min after the end of OX. The body temperature dropped to 37.2℃ with a single cylinder of flurbiprofen infusion. Case 2: A 64-year-old male with sigmoid colon cancer and liver metastases treated with BEV plus mFOLFOX6. After 3 h and 10 min since completion of OX, chills and a fever of 38.5℃ appeared. The body temperature was 38.3℃ 1 h after insertion of a 25-mg diclofenac suppository but dropped to 35.4℃ 10 h later. Case 3: A 76-year-old male. In the 8th course of mFOLFOX6 therapy for gastric cancer and peritoneal dissemination, 4 h and 45 min after completion of OX, the patient developed a fever of 38.3℃ with chills. Antipyretics were not used because of the patient's refusal, but the body temperature spontaneously decreased to 35.7℃ after 15 h. Although no DLST test was performed in any of the patients, we considered this to be an adverse reaction to OX, owing to lack of symptoms of chills or fever with 5-FU plus l-LV therapy except for OX. The patient should be treated with the knowledge that hypersensitivity reactions to OX do not occur only during the course of administration of OX.