The objectives of the study were to estimate the cost of medical care for patients recruited into the Trans Canada trial of Metastron (89Sr-chloride) as adjunct therapy in patients with prostate cancer metastatic to bone and to compare the costs of those receiving Metastron with those receiving placebo. Data from case report forms, hospital records and, where necessary, telephone follow-up were used. Twenty-nine patients, recruited into the trial at the Cross Cancer Institute, were followed from time of entry into the trial over the balance of their lifetime. Data were costed by reference to fee schedule, pharmacy and government and hospital defined costs as indirect (investigations, outpatient visits and total and tertiary hospital inpatient days) and direct (analgesics, hormones, radiotherapy and transfusions). Meaningful differences in analgesic, hormone and radiotherapy costs were seen between the two groups, with the group receiving Metastron showing a lifetime reduction of Can $1720 per person when compared with placebo. A reduction of Can $5696 per patient in the Metastron group was shown based upon requirements for admission for tertiary care; however, if total hospital stay costs are calculated there is no difference between the two groups. This retrospective study suggests that treatment with Metastron can bring about meaningful reductions in lifetime management costs in patients with advanced prostate cancer. These findings should be correlated with the significant improvement in quality of life reported in the Trans Canada study and appear to offer financial support to the clinical rationale for the use of Metastron in the palliative treatment of these patients.