This study evaluated the efficacy of prehospital external cardiac pacing in cardiac arrest patients. From October 1984 to June 1985, 91 patients were paced. Mean time from cardiac arrest to advanced life support (ALS) intervention in this metropolitan-rural ALS system was 14.5 minutes. Electrical capture occurred in 85 (93%), mechanical capture (pulses) occurred in ten (11%), and a measurable blood pressure occurred in three (3%) of the 91 patients. Despite a high rate of electrical capture, palpable pulses were produced only in 11%, and no patients survived to be discharged from the hospital. There was no difference in the frequency of electrical capture, palpable pulses, or outcome for patients receiving pharmacologic intervention before or after pacing. Likewise there was no difference in the frequency of electrical capture, palpable pulses, or outcome for patients receiving ALS therapy within or after ten minutes of their arrest. Although we found that external cardiac pacing was easily used in the prehospital setting, pacing did not result in any increase in survival in cardiac arrest patients.