206 participants, between the ages of 37 and 92, with knee or hip OA attending a general practitioner or who were referred to a hospital orthopaedic outpatient clinic to consider hip or knee joint replacement surgery, and who met the American College of Rheumatology clinical criteria for hip or knee OA, were randomly assigned in to 1 of 4 groups: Manual therapy, exercise therapy, combined manual and exercise therapy, or usual care (control), to analyze the cost effectiveness and benefit of these therapies, on patients with osteoarthritis of the hip or knee. Results of the study demonstrated that all three treatments resulted in increased quality-adjusted life years gains when compared to usual care and that from the New Zealand health system perspective, exercise therapy was the only treatment that resulted in an incremental cost utility ratio under 1 x GDP per capita at NZ$ 26,400. From the societal perspective manual therapy exhibited greater cost saving when compared to usual care for most scenarios studied and exercise therapy lead to increased cost utility ratios that were interpreted as cost effective, but were not cost saving. For the majority of scenarios analyzed in this study, combined therapy was not as cost effective as the other two therapies alone.