A program of care co-ordination (CC) in Melbourne for individuals with a history of high use of in-patient services was evaluated. The intervention involved care planning by a general practitioner (GP) and graduated case management depending on client health status. Services were purchased from pooled funds of participating health care agencies. A randomised control trial of 2,742 participants demonstrated no significant differences between the intervention and usual care group for two quality of life measures, the SF-36 and the AQoL (assessment of quality of life), and no difference in mortality rates. Total resource usage in the CC group was substantially higher, principally due to the extra costs for care planning and case management and for administering the CC model. Results conform to the higher costs typically found in other CC trials, although the failure to demonstrate improved client outcomes is less often reported. The reasons for this failure, whether in trial design, implementation, or theoretical underpinnings are explored in a companion paper.