BACKGROUND. Disparities in hospitalization

rates, particularly rates for avoidable hospital-izations, are indicators of potentially unmet health needs and inefficient use of health resources. Hospitalization rates that the Indian Health Service (IHS) can report underestimate disparities for American Indians (AIs) and Alaska Natives (ANs) relative to other Ameri-cans, because the IHS cannot track all hospi-talizations of AIs/ANs in their user population. OBJECTIVES. To compare hospitalization and avoidable hospitalization rates for a rural AI/AN user population with those of non-Indians living in the same counties where both groups use the same hospital system, regard-less of the expected source of payment. RESEARCH DESIGN. Retrospective analysis of California hospital discharge data for 1996 linked to rural IHS user data for 1995 and 1996 (3920 hospitalizations) compared with a ran-dom sample of discharge data for the rest of the non-Indian population in the 37 counties of the IHS Contract Health Service delivery area (7840 hospitalizations)