OBJECTIVES: Costs associated with anthracycline-induced cardiotoxic events (CE) are not known. To compare cost associated with CE among three cohort groups: anthracycline-containing-chemotherapy (ACC), no-anthracycline-containing-chemotherapy (NACC), and no-chemotherapy (control) groups within a U.S. managed care setting. METHODS: A retrospective cohort study was designed. Adult females (≥18) diagnosed with breast cancer between January 1, 2002 to December 31, 2005 (index-period) were identified. Subjects with previous CE, breast cancer diagnosis, or anthracycline-use 12-months prior to index date were excluded. Index date was defined as the first claim date for chemotherapy for ACC and NACC cohorts, and the first non-chemotherapy medication claim date for controls. ACC and NACC were matched to controls by month of index date and year of birth. Total healthcare costs were extracted from medical and pharmacy claims and summarized at per patient per year level. Cost of subjects developed CE were extracted from medical and pharmacy claims and were adjusted by using a gamma distributed generalized linear model with a log link function. RESULTS: A total of 21,106 subjects were classified as ACC (n=3,428), NACC (n=7,125) and controls (n=10,553). NACC cohort was significantly (p<.01) older (62 years ±12.5) compared to ACC (53±9.7) or control cohorts (59±12.5). ACC cohort had a higher (p<.01) degree of comorbidity, (1.8±0.8) compared to NACC (1.6±0.9) or control (1.3±0.8) as measured by Charlson comorbidity-index. At month 12 post index-date, 14% (n=485) of ACC and 5% (n=381) of NACC had CE compared to 3% (n=310) of controls. At 12 month post index, the unadjusted mean total health care costs per patient were $59,287, $20,528 and $11,600, respectively. The adjusted total health care costs for subjects developed CE were $45,304,951, $17,727,884 and $11,591,263 for ACC, NACC and controls, respectively. (p<.01) CONCLUSIONS: Health care cost for the ACC cohort was significantly higher than the NACC or controls cohorts.