We developed a decision support tool to assist physicians anticipating the need for antibiotic therapy. The initial screen alerts physicians of pertinent patient information, provides direct access to other essential medical information, and stimulates clinical judgment by suggesting an antibiotic regimen. The decision support tool also suggests the dose and interval for any ordered antibiotics selected by the physicians. During a 7-month pilot study, all antibiotics for patients admitted to the Shock/Trauma/Respiratory Intensive Care Unit (STRICU) were ordered using the decision support tool. Clinical data from the study period and a 12-month control period (the previous year) were collected and compared. The decision support tool was used to order antibiotics 588 times during the study period and the suggested antibiotics were used 218 (37%) times. The computer suggested dosages were used over 90% of the time. The mean cost of antibiotics was $87.00 (p < 0.04) less per patient during the study period as compared to the control period. Prospective assessment revealed only 3 antibiotic adverse drug events (ADEs) (0.9%) among 336 study patients as compared to 15 ADEs (2.4%) among 626 control patients (p = 0.164).