BACKGROUND: In the last decade, the number of new agents, including monoclonal antibodies, being developed to treat metastatic colorectal cancer (mCRC) increased rapidly. While improving outcomes, these new treatments also have distinct and known sfety profiles with toxicities that may require hospitalizations. However, patterns and costs of hospitalizations of toxicities of these new ‘targeted’ drugs are often unknown. OBJECTIVE: This study aimed to estimate the costs of hospital events associated with adverse events specified in the ‘Special Warnings and Precautions for Use’ section of the European Medicinal Agency Summary of Product Characteristics for bevacizumab, cetuximab, and panitumumab, in patients with mCRC. METHODS: From the PHARMO Record Linkage System (RLS), patients with a primary or secondary hospital discharge code for CRC and distant metastasis between 2000-2008 were selected and defined as patients with mCRC. The first discharge diagnosis defining metastases served as the indexdate. Patients were followed from index date until end of data collection, death, or end of study period, whichever occurred first. Hospital events during follow-up were identified through primary hospital discharge codes. Main outcomes for each event were length of stay and costs per hospital admission. RESULTS: Among 2964 mCRC patients, 271 hospital events occurred in 210 patients (mean [SD] duration of follow-up: 34  months). The longest mean (SD) length of stay per hospital admission were for stroke (16  days), arterial thromboembolism (ATE) (14  days), wound-healing complications (WHC), acute myocardial infarction (AMI), congestive heart failure (CHF), and neutropenia (all 9 days; SD 5-15). Highest mean (SD) costs per admission were for stroke (euro13,500 [euro28,800]), ATE (euro13,300 [euro18,800]), WHC (euro10,800 [euro20,500]). LIMITATIONS: Although no causal link could be identified between any specific event and any specific treatment, data from this study are valuable for pharmacoeconomic evaluations of newer treatments in mCRC patients. CONCLUSIONS: Inpatient costs for events in mCRC patients are considerable and vary greatly.