To determine trends in characteristics of total hip arthroplasty (THA) in the United States, the National Hospital Discharge Survey (NHDS) was analyzed from 1990 to 2004 for trends in in-hospital mortality and complications, length of hospital stay, demographics, and comorbidities. The number of THAs performed increased by 158%, whereas mortality rates remained low and slightly decreased (from 0.32% to 0.29%). Prevalence of procedure-related complications decreased over time, and length of stay decreased from an average of 8.7 days to 4.5 days. These improvements occurred despite an increase in comorbidities in patients. An increase in both the proportion of discharges to long- and short-term care facilities and in the proportion of procedures performed in smaller hospitals was noted. Multiple temporal changes in outcomes and demographics for THA were found. These changes have implications for clinical care and allocation of health resources.