The Norwegian Knowledge Centre for the Health Services has been commissioned by Norwegian Directorate of Health’s Cancer Programme to make an assessment of the cost per progression-free year gained associated with the use of bevacizumab in combination with paclitaxel versus paclitaxel alone, as first line treatment for metastatic breast cancer. The result is likely to have bearings on a possible revision of the treatment guidelines for breast cancer in Norway. We developed a health economic model of the Markov type in which we compared data from a clinical study, Miller et al . 2007, with Norwegian cost data associated with the treatment alternatives. Mean progression-free time in the group treated with bevacizumab+paclitaxel was 1 1.2 years whereas it was 0.73 years in the comparator group. This resulted in an incremental effect of 0,47 progression-free years. With regard to quality of life, the incremental effect was 0.2 QALYs. We estimated the incremental costs associated with use of bevacizumab+paclitaxel from a health service perspective to be NOK 765 000, which translates into a cost per progression-free life year gained of NOK 1.6 million and a cost per QALY gained of NOK 3.8 million. The estimate from the societal perspective, where tax, value-added tax and social security payments were deducted, was approx. NOK 1.3 million per progression-free life-year and NOK 3 million per QALY gained. The cost per progression-free year gained is relatively high, and the cost per QALY gained is higher than cost-effective thresholds which have been proposed in Norway.