OBJECTIVES: MBD secondary to cancer can result in serious and costly SREs.  The objective of this study was to characterise hospital burden associated with MBD and SREs following BC and PC in the UK. METHODS: Data were analysed from the CHKS database (Apri, 1, 1999-March 31, 2006), which collects inpatient episode data for England, Wales, Scotland, and Northern Ireland, representing 70% of hospitalizations in the UK.  Patients with an index inpatient admission for either female BC (ICD-10 C50*) or PC (ICD-10 C61*) between January 4, 2003 and March 31, 2004 were selected for analysis and followed until March 31, 06 for subsequent admissions of MBD (ICD-10 C79.5*) and SREs (pathological fractures, spinal cord compressions, bone surgery), which were identified using ICD-10 codes for diagnoses and OPCS 4.3 codes for procedures.  Hospital length of stay (LOS) and inpatient costs were analysed by cancer type and disease stage (index, MBD, or SRE).  RESULTS: A total of 38,975 patients were identified with BC and 28,130 with PC.  The 3-year incidence rates/1000 for hospital admissions, including MBD diagnosis code and MBD&SRE diagnosis codes, were 71.7 and 9.2 for BC and 163.5 and 18.6 for PC.  Readmissions were consistent across cancer types, with MBD&SRE patients having the greatest number of readmissions (BC: 80%; PC: 81%) compared with patients with cancer diagnosis only (BC: 41%; PC: 42%) and patients with cancer&MBD (BC: 75%; PC: 73%).  Additionally, patients developing MBD&SREs had greater mean total LOS (BC: 40 days; PC: 43 days) than those with cancer only (BC: 8 days; PC: 12 days), and those with cancer&MBD (BC: 24 days; PC: 28 days).  Mean cost of admissions increased as the disease progressed from cancer only to MBD&SREs for BC and PC patients (£2215-£4158 and £1871-£3618, respectively).  CONCLUSIONS: In general, UK patients with BC and PC, who develop SREs secondary to MBD consume greater hospital resources than those with cancer or MBD only.