We reviewed the records of 25 colon cancer patients consecutively treated with an oxaliplatin-containing regimen. We differentiated between hypersensitivity reactions and pain reactions due to oxaliplatin. The patients did not receive preventive pre-medication. Four patients underwent an adverse reaction. Three patients fulfilled the criteria of a hypersensitivity reaction with tachycardia, chills and hyperhidrosis. In addition, two patients suffered from severe abdominal and chest pain. Reactions occurred during or shortly after the oxaliplatin infusion. All patients recovered under symptomatic therapy. After reacting for the first time, pre-medication was applied prior to the oxaliplatin infusion. However, due to further reactions, the treatment protocol had to be changed in all cases into a regimen not containing oxaliplatin. We conclude that adverse reactions are relatively frequent toxic side-effects of oxaliplatin, mainly in heavily pre-treated patients. Pre-medication was ineffective in preventing further reactions and consequently the treatment regimen had to be changed in all cases.