A random sample survey of 500 acute care hospitals in the United States was conducted to evaluate the adoption of extended-interval aminoglycoside dosing (EIAD). The survey revealed that EIAD has been adopted in 3 of every 4 acute care hospitals, a 4-fold increase since 1993. Of the 74.7% of hospitals reporting EIAD, 64% had written guidelines. Equal or less toxicity (87.1%), equal efficacy (76.9%), and cost-savings (65.6%) were common rationales. There has been a trend toward higher adult dosages of gentamicin (e.g., >5 mg/kg/dose) and an increase in the adoption of EIAD across all age groups (neonatal, 11%, and pediatric, 23%). Monitoring of aminoglycoside concentrations has shifted to a single determination of concentration, at 6-18 h after drug administration. The most common methods of dosage adjustment for declining renal function were an interval extension with the same dose (47%) or use of the Hartford nomogram (32%).