Computerized drug-interaction screening systems (CDISS) have been developed as a tool to help decrease the enormous morbidity and expense related to adverse drug interactions. In previous studies the CDISS was used primarily by pharmacists in hospital settings to screen for interactions after the prescription had been written. This study tests the feasibility of family physicians using CDISS before writing the prescription to allow for changes in the prescription while the patient is still in the office. In a 30-day period, 103 patients were screened by family physicians for potential drug-drug, drug-alcohol, and drug-food interactions. Potential drug interactions of varying clinical significance were detected for 71 patients (68.9 percent). The prescription plan was changed for 16 patients (15.5 percent) as a result of using the CDISS. Participating physicians reported that they gained new information in 45.8 percent of the patient encounters, that their awareness of the potential for drug interactions was heightened by participation in this study, and that their exposure to the CDISS was worthwhile as an educational tool. While a few problems, mainly logistic, were noted with the CDISS as used in this study, the authors conclude that with modifications a CDISS can be of great educational and clinical value to the family physician and his or her patients.