OBJECTIVES: To describe chemotherapy regimens used in the first, second, third and fourth-line of treatment in patients with metastatic colorectal cancer. Costs of chemotherapy regimens used as well as supportive care and medical procedures in Bulgaria will be estimated (as part of a multinational central European study). METHODS: This opinion-based study collected required data by online questionnaire. All information concerning treatment of colorectal cancer was based on experts opinion from four oncology centers in Bulgaria. Oncologists had access to medical records of approximately 1220 patients treated in year 2008. RESULTS: The leading first line regimen (60% of patients) was FOLFOX 4 (oxaliplatin, calcium folinate, fluorouracil). The most commonly prescribed second-line regimen (50%) was FOLFIRI (irinotecan, calcium folinate, fluorouracil). Capecitabine was the most popular in both the third- (26%) and fourth-line (4%) settings. The percentage of patients receiving supportive care increased with disease stage, from 1% in the first, 21% in the second, 53% in the third and 94% in the fourth-line. The most common treatment algorithm (18%) was FOLFOX, FOLFIRI and supportive care in the first-, second- and third-lines, respectively. Mean regimen costs per patient were estimated from a public payer perspective. The most expensive first, second, third and fourth-line regimens were FOLFOX 4 (€14,200), FOLFIRI + bevacizumab (€7,912€), cetuximab + irinotecan (€7,237) and capecitabine (€2,609), respectively. CONCLUSIONS: The most common regimen in the first line was also the most expensive one. New chemotherapeutic agents are associated with improvements in survival time but also with substantial costs. Factors influencing the selection of chemotherapy included: previous therapies, course of the disease, the patient’s performance status, adverse events after previous chemotherapies and concomitant diseases. However, open-ended coverage policies for new chemotherapeutic agents may prove difficult to sustain as costs continue to rise.