Antibiotics are often used inappropriately in hospitals. We created a structured antibiotic order form designed to guide physicians toward correct therapeutic decisions without restricting their clinical options. Educational messages and graphic reminders were incorporated into a new form required to order parenteral antibiotics at a teaching hospital. Pharmacokinetic considerations were emphasized. The forms were supplemented with brief literature reviews and appropriate references. Before introduction of the form, pharmacokinetically incorrect orders for clindamycin, cefazolin sodium, and metronidazole hydrochloride accounted for 90%, 60%, and 75% of patient-days of therapy for these drugs, respectively. Immediately after implementation of the form, nonrecommended dosing schedules dropped to under 6% of patient-days for all three antibiotics. Savings from these drugs alone accounted for over $76,000 annually. We conclude that in a period of increasing constraints on hospital budgets and proliferating restrictions on physicians' clinical choices, educational intervention at the time orders are written can provide a cost-effective and noncoercive means of improving some forms of acute-care clinical decision making.