OBJECTIVES: Monoclonal antibody (mAb) therapies for the treatment of metastatic colorectal cancer (mCRC) are associated with a risk of infusion reactions, though the rates of infusion reactions differ among mAbs. Currently there is limited published data on the clinical and economic impact of infusion reactions. The objective of this study was to investigate the resource use associated with infusion reactions and the impact of these reactions on patient management in real-world clinical practice in Europe.  METHODS: Eighty oncologists and nurses from eight European countries (Denmark, France, Germany, Greece, Italy, Spain, Sweden and the UK) were interviewed by telephone over a 6-week period in 2010. To be included, the respondents (10 from each country) must be currently treating patients with mCRC.  Each telephone interview lasted 30-45 minutes using a questionnaire (16 questions) specifically developed for this study.  RESULTS: The mean number of total staff (including physicians and nurses) involved in managing an infusion reaction was 1.97 for a grade 1 infusion reaction, 2.35 for a grade 2 infusion reaction, 3.60 for a grade 3 infusion reaction and 5.30 for a grade 4 infusion reaction. For grade 3 infusion reactions, the majority of patients (73.4%) were treated in a hospital inpatient setting; while for grade 4 infusion reactions, the majority of patients (82.5%) were treated in intensive care. Treatment duration in hospitals for infusion reactions also increased with the severity. Among patients hospitalized for infusion reactions, grade 3 infusion reactions were treated for a mean of half day (13.3 (± 29) hours) in intensive care compared to a mean of 2 days (48.1 (± 43.7) hours) for grade 4 infusion reactions.  CONCLUSIONS: In conclusion, infusion reactions led to substantial resource use, which increased with the severity of the infusion reactions in real-world clinical practice across eight European countries.