OBJECTIVES: Summary physical and mental health scores for the Short Form (SF) measures assume that physical and mental health are uncorrelated. The Rand Health Status Inventory (HSI) measures allow correlation and also employ item weights derived from item-response theory. Do these different approaches to scoring matter? The objective was to compare summary scores using both the SF and Rand HSI. METHODS: SF-36 and the Health Utilities Index Mark 3 (HUI3) were administered to a cohort of patients waiting for elective total hip arthroplasty (THA). SF-12 and HUI3 were administered to a cohort of high-risk primary-care patients. Summary scores were generated and compared. Single-attribute utility scores for emotion in HUI3 were also computed. Canadian and U.S norms for SF, Rand HSI, and HUI3 were used to interpret results. RESULTS: For THA patients mean physical health scores were 28 and 36 for SF and Rand HSI. Mean mental health scores were 55 and 42. For the primary-care patients the scores were 34 and 36 for physical and 46 and 40 for mental health. HUI3 emotion scores for the primary-care patients were well below population norm. CONCLUSIONS: SF and Rand HSI provided similar summary scores in the THA study. However, SF and Rand HSI mental health scores differed in the primary-care patient cohort and results from HUI3 corroborate the mental health deficits identified by the Rand HSI. It may be wise for investigators to utilize both SF and Rand HSI scoring systems.