A prospective program to convert patients from parenteral to oral antibiotics was evaluated over 12 months to determine its pharmacoeconomic impact on antibiotic acquisition and length of hospital stay. Physicians of patients meeting predetermined clinical criteria for mild and moderate infections were contacted to discuss potential oral alternative therapy. Clinical end points and economic data were followed in 242 patients (200 converted and 42 not converted but meeting criteria). No significant differences were noted between the groups with regard to demographic data, infection diagnosis, clinical outcome, or adverse effects. The average number of days of therapy for patients converted was 1.53 days shorter than that of patients who were not converted to oral therapy (p < 0.003). Cost savings for drug acquisition and length of stay were $15,149.24 and $161,071.88, respectively. The intervention program appeared to provide a cost-effective conversion from parenteral to oral antimicrobial administration without compromising patient care. It is anticipated that expansion of the program to include additional antibiotics will result in even greater cost savings for the institution.