Breast cancer is the most common cancer among Swedish women and an important cause of illness and death. The aim of this study was to estimate the total cost of breast cancer in Sweden in 2002, using a top-down prevalence-based cost-of-illness approach. The total cost of breast cancer in Sweden in 2002 was estimated at 3.0 billion SEK (1 euro = 9.4 SEK). The direct costs were estimated at 895 million SEK and constituted 30% of the total cost. Indirect costs were estimated at 2.1 billion SEK and constituted 70% of the total cost. The main cost driver was production losses caused by premature mortality, amounting to 52% of the indirect costs. The reason that indirect costs were the dominant cost is because most newly detected breast cancers occur in patients aged below 65, thus causing significant production losses due to sick leave, early retirement, and premature mortality.