A prospective series of 108 Emergency Department attendees over a six-month period with a clinical diagnosis of unstable angina for whom anticoagulation with heparin was prescribed were included in the study. The standard regime was a 5000 unit bolus followed by an intravenous infusion of 1000 units per hour (1200 units if the patient's weight was greater than 80 kg), with subsequent adjustments being made by reference to a nomogram