OBJECTIVE To identify the extent of inappropriate prescribing using criteria for proper use developed by the Agency for Healthcare Research and Quality (AHRQ) and dose-limitation criteria defined by Beers, as well as to describe duration of use and patient characteristics associated with inappropriate prescribing for older people. METHODS Retrospective national Veterans Health Administration (VA) administrative database analysis. METHODS VA outpatient facilities during fiscal year 2000 (FY00). METHODS Veterans aged 65 and older having at least one VA outpatient visit in FY00 (N=1,265,434). METHODS Operational definitions of appropriate use were developed based on recommendations of an expert panel convened by the AHRQ (Zhan criteria). Inappropriate use was identified based on these criteria and inappropriate use of drugs per Beers criteria for dose-limitations in older people. Furthermore, duration of use and patient characteristics associated with inappropriate use were described. RESULTS After adjusting for diagnoses, dose, and duration, inappropriate prescribing decreased from 33% to 23%. Exposure to inappropriate drugs was prolonged. Pain relievers, benzodiazepines, antidepressants, and musculoskeletal agents constituted 61% of inappropriate prescribing. Whites, patients with psychiatric comorbidities, and patients receiving more medications were most likely to receive inappropriate drugs. Women were more likely to receive Zhan criteria drugs; men were more likely to receive dose-limited drugs CONCLUSIONS For the most part, the Zhan criteria did not explain inappropriate prescribing, which includes problems related to dose and duration of prescriptions. Interventions targeted at prescriptions for pain relievers, benzodiazepines, antidepressants, and musculoskeletal agents may dramatically decrease inappropriate prescribing and improve patient outcomes.