A nationwide network of clinical pharmacists has been organized for the purpose of collecting drug experience data generated during the routine clinical care of patients. In order to assess the utility of this network a pilot project was performed to obtain a cross-sectional view of antibiotic utilization in the U.S. and to identify potential problems with a more widespread implementation of this program. One hundred eleven pharmacists enrolled in the drug surveillance network participated in this survey and collected information on more than 2000 patients treated with antimicrobial agents over approximately a three-month period (February-April 1987). The most common sites of infection were the lung, genitourinary tract, skin and soft tissue, and the abdomen, and accounted for approximately 75 percent of infections. Overall, the aminoglycosides, the first-generation cephalosporins, and the aminopenicillins remain the most commonly used antibiotics and represent approximately 50 percent of antimicrobials used in the surveyed population. The results of this pilot project suggest that the use of a nationwide network of clinical pharmacists is a promising source of clinically relevant drug experience data. The ability to concurrently evaluate patients and link information regarding patient demographics, drug therapy regimens, diagnosis, and clinical outcomes fills an important gap in our knowledge of clinical drug utilization.