This report describes the departmental and laboratory use of integrated, hospital-wide computing systems at Beth Israel and Brigham and Women's hospitals in Boston. The systems have an important role in the admitting, outpatient, and medical records departments; in the clinical departments (blood bank, cardiology, neurophysiology, pathology, radiology, and pharmacy); in the clinical laboratories; and at Brigham and Women's Hospital, in the financial departments. Information that is collected in the computers from these departments and laboratories is available for viewing by clinicians at terminals located throughout each hospital and is used in compiling charges for each patient's account. The programs are heavily used. During a one-week study period, 742 departmental and laboratory workers at Beth Israel Hospital filed or edited information in patients' computerized records 137,526 times. During the same week, 984 departmental and laboratory workers at Brigham and Women's Hospital filed or edited information 293,367 times. After the computing systems were introduced, the time required to collect unpaid bills decreased substantially at both hospitals.