We developed and evaluated a system to automatically identify serious clinical conditions in inpatients. The system notifies the patient's covering physician via his pager that an alert is present and offers potential therapies for the patient's condition (action items) at the time he views the alert information. Over a 6 month period, physicians responded to 1214 (70.2%) of 1730 alerts for which they were paged; they responded to 1002 (82.5% of the 1214) in less than 15 minutes. They said they would take action in 71.5% of the alerts, and they placed an order directly from the alert display screen in 39.4%. Further study is needed to determine if this alerting system improves processes or outcomes of care.