OBJECTIVE: Breast cancer is one of the major causes of premature death for women. The management of its cost is important for both the national health insurance and the individual health-care providers. The objective of this study was to assess the global medical cost of breast cancer, from diagnosis to follow up, in a French medical centre. METHODS: Our evaluation was based on a retrospective cohort of 120 patients followed from January 1995 to February 2000 at Centre René Huguenin (Saint-Cloud). Comprehensive treatment schemes and clinical events were reported from patients' medical files. Detailed medical consumptions and mean duration of staff occupation were obtained primarily from direct observation of the Centre's activities, for each modality of patient follow-up and treatment (surgery, radiotherapy, chemotherapy, consultations). Unit costs were obtained from cost accounts of the Centre. Medical cost of breast cancer was computed from the cancer Centre perspective, by adding micro-costing and macro-costing components. RESULTS: The mean medical cost per patient was €10 072 [95% CI 9 195 ; 10 948]. Costs per patient ranged from €2 813 to €36 170. Median cost was of € 8 860. The initial treatment phase represented the most expensive component, reaching €7 378 [7 040 ; 7 717] on average, which amounted to 73.3 % of the global cost. CONCLUSION: This study has provided an estimate of the global cost of managing patients with breast cancer in a French Comprehensive Cancer Centre (CLCC). Our estimates were consistent with those of the French national database of costs per DRG. However, our approach has the advantage of providing a cost per patient suitable for cost-of-illness evaluations, rather than a cost per hospital stay.